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Alkali metal | Applications | Applications
Lithium, sodium, and potassium have many useful applications, while rubidium and caesium are very notable in academic contexts but do not have many applications yet. Lithium is the key ingredient for a range of lithium-based batteries, and lithium oxide can help process silica. Lithium stearate is a thickener and can be used to make lubricating greases; it is produced from lithium hydroxide, which is also used to absorb carbon dioxide in space capsules and submarines. Lithium chloride is used as a brazing alloy for aluminium parts. In medicine, some lithium salts are used as mood-stabilising pharmaceuticals. Metallic lithium is used in alloys with magnesium and aluminium to give very tough and light alloys.
Sodium compounds have many applications, the most well-known being sodium chloride as table salt. Sodium salts of fatty acids are used as soap. Pure sodium metal also has many applications, including use in sodium-vapour lamps, which produce very efficient light compared to other types of lighting, and can help smooth the surface of other metals. Being a strong reducing agent, it is often used to reduce many other metals, such as titanium and zirconium, from their chlorides. Furthermore, it is very useful as a heat-exchange liquid in fast breeder nuclear reactors due to its low melting point, viscosity, and cross-section towards neutron absorption. Sodium-ion batteries may provide cheaper alternatives to their equivalent lithium-based cells. Both sodium and potassium are commonly used as GRAS counterions to create more water-soluble and hence more bioavailable salt forms of acidic pharmaceuticals.
Potassium compounds are often used as fertilisers as potassium is an important element for plant nutrition. Potassium hydroxide is a very strong base, and is used to control the pH of various substances. Potassium nitrate and potassium permanganate are often used as powerful oxidising agents. Potassium superoxide is used in breathing masks, as it reacts with carbon dioxide to give potassium carbonate and oxygen gas. Pure potassium metal is not often used, but its alloys with sodium may substitute for pure sodium in fast breeder nuclear reactors.
Rubidium and caesium are often used in atomic clocks. Caesium atomic clocks are extraordinarily accurate; if a clock had been made at the time of the dinosaurs, it would be off by less than four seconds (after 80 million years). For that reason, caesium atoms are used as the definition of the second. Rubidium ions are often used in purple fireworks, and caesium is often used in drilling fluids in the petroleum industry.
Francium has no commercial applications, but because of francium's relatively simple atomic structure, among other things, it has been used in spectroscopy experiments, leading to more information regarding energy levels and the coupling constants between subatomic particles. Studies on the light emitted by laser-trapped francium-210 ions have provided accurate data on transitions between atomic energy levels, similar to those predicted by quantum theory. |
Alkali metal | Biological role and precautions | Biological role and precautions |
Alkali metal | Metals | Metals
Pure alkali metals are dangerously reactive with air and water and must be kept away from heat, fire, oxidising agents, acids, most organic compounds, halocarbons, plastics, and moisture. They also react with carbon dioxide and carbon tetrachloride, so that normal fire extinguishers are counterproductive when used on alkali metal fires. Some Class D dry powder extinguishers designed for metal fires are effective, depriving the fire of oxygen and cooling the alkali metal.
Experiments are usually conducted using only small quantities of a few grams in a fume hood. Small quantities of lithium may be disposed of by reaction with cool water, but the heavier alkali metals should be dissolved in the less reactive isopropanol. The alkali metals must be stored under mineral oil or an inert atmosphere. The inert atmosphere used may be argon or nitrogen gas, except for lithium, which reacts with nitrogen. Rubidium and caesium must be kept away from air, even under oil, because even a small amount of air diffused into the oil may trigger formation of the dangerously explosive peroxide; for the same reason, potassium should not be stored under oil in an oxygen-containing atmosphere for longer than 6 months. |
Alkali metal | Ions | Ions
thumb|right|Lithium carbonate
The bioinorganic chemistry of the alkali metal ions has been extensively reviewed.
Solid state crystal structures have been determined for many complexes of alkali metal ions in small peptides, nucleic acid constituents, carbohydrates and ionophore complexes.
Lithium naturally only occurs in traces in biological systems and has no known biological role, but does have effects on the body when ingested. Lithium carbonate is used as a mood stabiliser in psychiatry to treat bipolar disorder (manic-depression) in daily doses of about 0.5 to 2 grams, although there are side-effects. Excessive ingestion of lithium causes drowsiness, slurred speech and vomiting, among other symptoms, and poisons the central nervous system, which is dangerous as the required dosage of lithium to treat bipolar disorder is only slightly lower than the toxic dosage. Its biochemistry, the way it is handled by the human body and studies using rats and goats suggest that it is an essential trace element, although the natural biological function of lithium in humans has yet to be identified.
Sodium and potassium occur in all known biological systems, generally functioning as electrolytes inside and outside cells. Sodium is an essential nutrient that regulates blood volume, blood pressure, osmotic equilibrium and pH; the minimum physiological requirement for sodium is 500 milligrams per day. Sodium chloride (also known as common salt) is the principal source of sodium in the diet, and is used as seasoning and preservative, such as for pickling and jerky; most of it comes from processed foods. The Dietary Reference Intake for sodium is 1.5 grams per day, but most people in the United States consume more than 2.3 grams per day, the minimum amount that promotes hypertension; this in turn causes 7.6 million premature deaths worldwide.
Potassium is the major cation (positive ion) inside animal cells, while sodium is the major cation outside animal cells. The concentration differences of these charged particles causes a difference in electric potential between the inside and outside of cells, known as the membrane potential. The balance between potassium and sodium is maintained by ion transporter proteins in the cell membrane. The cell membrane potential created by potassium and sodium ions allows the cell to generate an action potential—a "spike" of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function. Disruption of this balance may thus be fatal: for example, ingestion of large amounts of potassium compounds can lead to hyperkalemia strongly influencing the cardiovascular system. Potassium chloride is used in the United States for lethal injection executions.
thumb|400px|right|A wheel type radiotherapy device which has a long collimator to focus the radiation into a narrow beam. The caesium-137 chloride radioactive source is the blue square, and gamma rays are represented by the beam emerging from the aperture. This was the radiation source involved in the Goiânia accident, containing about 93 grams of caesium-137 chloride.
Due to their similar atomic radii, rubidium and caesium in the body mimic potassium and are taken up similarly. Rubidium has no known biological role, but may help stimulate metabolism, and, similarly to caesium, replace potassium in the body causing potassium deficiency. Partial substitution is quite possible and rather non-toxic: a 70 kg person contains on average 0.36 g of rubidium, and an increase in this value by 50 to 100 times did not show negative effects in test persons. Rats can survive up to 50% substitution of potassium by rubidium. Rubidium (and to a much lesser extent caesium) can function as temporary cures for hypokalemia; while rubidium can adequately physiologically substitute potassium in some systems, caesium is never able to do so. There is only very limited evidence in the form of deficiency symptoms for rubidium being possibly essential in goats; even if this is true, the trace amounts usually present in food are more than enough.
Caesium compounds are rarely encountered by most people, but most caesium compounds are mildly toxic. Like rubidium, caesium tends to substitute potassium in the body, but is significantly larger and is therefore a poorer substitute. Excess caesium can lead to hypokalemia, arrhythmia, and acute cardiac arrest, but such amounts would not ordinarily be encountered in natural sources. As such, caesium is not a major chemical environmental pollutant. The median lethal dose (LD50) value for caesium chloride in mice is 2.3 g per kilogram, which is comparable to the LD50 values of potassium chloride and sodium chloride. Caesium chloride has been promoted as an alternative cancer therapy, but has been linked to the deaths of over 50 patients, on whom it was used as part of a scientifically unvalidated cancer treatment.Wood, Leonie.
Radioisotopes of caesium require special precautions: the improper handling of caesium-137 gamma ray sources can lead to release of this radioisotope and radiation injuries. Perhaps the best-known case is the Goiânia accident of 1987, in which an improperly-disposed-of radiation therapy system from an abandoned clinic in the city of Goiânia, Brazil, was scavenged from a junkyard, and the glowing caesium salt sold to curious, uneducated buyers. This led to four deaths and serious injuries from radiation exposure. Together with caesium-134, iodine-131, and strontium-90, caesium-137 was among the isotopes distributed by the Chernobyl disaster which constitute the greatest risk to health. Radioisotopes of francium would presumably be dangerous as well due to their high decay energy and short half-life, but none have been produced in large enough amounts to pose any serious risk. |
Alkali metal | Notes | Notes |
Alkali metal | References | References
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Alkali metal | Table of Content | short description, History, Occurrence, In the Solar System, On Earth, Properties, Physical and chemical, Lithium, Francium, Nuclear, Periodic trends, Atomic and ionic radii, First ionisation energy, Reactivity, Electronegativity, Melting and boiling points, Density, Compounds, [[Hydroxides]], Intermetallic compounds, Compounds with the group 13 elements, Compounds with the group 14 elements, Nitrides and pnictides, Oxides and chalcogenides, Halides, hydrides, and pseudohalides, Coordination complexes, Ammonia solutions, Organometallic, Organolithium, Heavier alkali metals, Representative reactions of alkali metals, Reaction with oxygen, Reaction with sulfur, Reaction with nitrogen, Reaction with hydrogen, Reaction with carbon, Reaction with water, Reaction with other salts, Reaction with organohalide compounds, Alkali metals in liquid ammonia, Extensions, Pseudo-alkali metals, Hydrogen, Ammonium and derivatives, Cobaltocene and derivatives, Thallium, Copper, silver, and gold, Production and isolation, Applications, Biological role and precautions, Metals, Ions, Notes, References |
Alphabet | Short description | An alphabet is a standard set of letters written to represent particular sounds in a spoken language. Specifically, letters largely correspond to phonemes as the smallest sound segments that can distinguish one word from another in a given language. Not all writing systems represent language in this way: a syllabary assigns symbols to spoken syllables, while logographies assign symbols to words, morphemes, or other semantic units.
The first letters were invented in Ancient Egypt to serve as an aid in writing Egyptian hieroglyphs; these are referred to as Egyptian uniliteral signs by lexicographers. This system was used until the 5th century AD, and fundamentally differed by adding pronunciation hints to existing hieroglyphs that had previously carried no pronunciation information. Later on, these phonemic symbols also became used to transcribe foreign words. The first fully phonemic script was the Proto-Sinaitic script, also descending from Egyptian hieroglyphs, which was later modified to create the Phoenician alphabet. The Phoenician system is considered the first true alphabet and is the ultimate ancestor of many modern scripts, including Arabic, Cyrillic, Greek, Hebrew, Latin, and possibly Brahmic.
thumb|Corresponding letters in the Phoenician and Latin alphabets
Peter T. Daniels distinguishes true alphabets—which use letters to represent both consonants and vowels—from both abugidas and abjads, which only need letters for consonants. Abjads generally lack vowel indicators altogether, while abugidas represent them with diacritics added to letters. In this narrower sense, the Greek alphabet was the first true alphabet; it was originally derived from the Phoenician alphabet, which was an abjad.
Alphabets usually have a standard ordering for their letters. This makes alphabets a useful tool in collation, as words can be listed in a well-defined order—commonly known as alphabetical order. This also means that letters may be used as a method of "numbering" ordered items. Some systems demonstrate acrophony, a phenomenon where letters have been given names distinct from their pronunciations. Systems with acrophony include Greek, Arabic, Hebrew, and Syriac; systems without include the Latin alphabet. |
Alphabet | Etymology | Etymology
The English word alphabet came into Middle English from the Late Latin word , which in turn originated in the Greek ; it was made from the first two letters of the Greek alphabet, alpha (α) and beta (β). The names for the Greek letters, in turn, came from the first two letters of the Phoenician alphabet: aleph, the word for ox, and bet, the word for house. |
Alphabet | History | History |
Alphabet | Alphabets related to Phoenician | Alphabets related to Phoenician |
Alphabet | Ancient Near Eastern alphabets | Ancient Near Eastern alphabets
The Ancient Egyptian writing system had a set of some 24 hieroglyphs that are called uniliterals, which are glyphs that provide one sound. These glyphs were used as pronunciation guides for logograms, to write grammatical inflections, and, later, to transcribe loan words and foreign names. The script was used a fair amount in the 4th century AD. However, after pagan temples were closed down, it was forgotten in the 5th century until the discovery of the Rosetta Stone. There was also cuneiform, primarily used to write several ancient languages, including Sumerian. The last known use of cuneiform was in 75 AD, after which the script fell out of use.
In the Middle Bronze Age, an apparently alphabetic system known as the Proto-Sinaitic script appeared in Egyptian turquoise mines in the Sinai Peninsula , apparently left by Canaanite workers. Orly Goldwasser has connected the illiterate turquoise miner graffiti theory to the origin of the alphabet. In 1999, American Egyptologists John and Deborah Darnell discovered an earlier version of this first alphabet at the Wadi el-Hol valley. The script dated to and shows evidence of having been adapted from specific forms of Egyptian hieroglyphs that could be dated to , strongly suggesting that the first alphabet had developed about that time. The script was based on letter appearances and names, believed to be based on Egyptian hieroglyphs. This script had no characters representing vowels. Originally, it probably was a syllabary—a script where syllables are represented with characters—with symbols that were not needed being removed. The best-attested Bronze Age alphabet is Ugaritic, invented in Ugarit before the 15th century BC. This was an alphabetic cuneiform script with 30 signs, including three that indicate the following vowel. This script was not used after the destruction of Ugarit in 1178 BC.Ugaritic Writing online
thumb|left|A specimen of the Proto-Sinaitic script, one of the earliest phonemic scripts
The Proto-Sinaitic script eventually developed into the Phoenician alphabet, conventionally called Proto-Canaanite, before . The oldest text in Phoenician script is an inscription on the sarcophagus of King Ahiram . This script is the parent script of all western alphabets. By the 10th century BC, two other forms distinguish themselves, Canaanite and Aramaic. The Aramaic gave rise to the Hebrew alphabet.
The South Arabian alphabet, a sister script to the Phoenician alphabet, is the script from which the Geʽez script was descended. Abugidas are writing systems with characters comprising consonant–vowel sequences. Alphabets without obligatory vowels are called abjads, with examples being Arabic, Hebrew, and Syriac. The omission of vowels was not always a satisfactory solution due to the need of preserving sacred texts. "Weak" consonants are used to indicate vowels. These letters have a dual function since they can also be used as pure consonants.
The Proto-Sinaitic script and the Ugaritic script were the first scripts with a limited number of signs instead of using many different signs for words, in contrast to cuneiform, Egyptian hieroglyphs, and Linear B. The Phoenician script was probably the first phonemic script, and it contained only about two dozen distinct letters, making it a script simple enough for traders to learn. Another advantage of the Phoenician alphabet was that it could write different languages since it recorded words phonemically.
The Phoenician script was spread across the Mediterranean by the Phoenicians. The Greek alphabet was the first in which vowels had independent letterforms separate from those of consonants. The Greeks chose letters representing sounds that did not exist in Greek to represent vowels. The Linear B syllabary, used by Mycenaean Greeks from the 16th century BC, had 87 symbols, including five vowels. In its early years, there were many variants of the Greek alphabet, causing many different alphabets to evolve from it. |
Alphabet | European alphabets | European alphabets
The Greek alphabet, in Euboean form, was carried over by Greek colonists to the Italian peninsula giving rise to many different alphabets used to write the Italic languages, like the Etruscan alphabet. One of these became the Latin alphabet, which spread across Europe as the Romans expanded their republic. After the fall of the Western Roman Empire, the alphabet survived in intellectual and religious works. It came to be used for the Romance languages that descended from Latin and most of the other languages of western and central Europe. Today, it is the most widely used script in the world.
The Etruscan alphabet remained nearly unchanged for several hundred years. Only evolving once the Etruscan language changed itself. The letters used for non-existent phonemes were dropped. Afterwards, however, the alphabet went through many different changes. The final classical form of Etruscan contained 20 letters. Four of them are vowels——six fewer letters than the earlier forms. The script in its classical form was used until the 1st century AD. The Etruscan language itself was not used during the Roman Empire, but the script was used for religious texts.
Some adaptations of the Latin alphabet have ligatures, a combination of two letters make one, such as æ in Danish and Icelandic and in Algonquian; borrowings from other alphabets, such as the thorn in Old English and Icelandic, which came from the Futhark runes; and modified existing letters, such as the eth of Old English and Icelandic, which is a modified d. Other alphabets only use a subset of the Latin alphabet, such as Hawaiian and Italian, which uses the letters j, k, x, y, and w only in foreign words.
Another notable script is Elder Futhark, believed to have evolved out of one of the Old Italic alphabets. Elder Futhark gave rise to other alphabets known collectively as the Runic alphabets. The Runic alphabets were used for Germanic languages from 100 AD to the late Middle Ages, being engraved on stone and jewelry, although inscriptions found on bone and wood occasionally appear. These alphabets have since been replaced with the Latin alphabet. The exception was for decorative use, where the runes remained in use until the 20th century.Stifter, David (2010), "Lepontische Studien: Lexicon Leponticum und die Funktion von san im Lepontischen", in Stüber, Karin; et al. (eds.), Akten des 5. Deutschsprachigen Keltologensymposiums. Zürich, 7.–10. September 2009, Wien.
thumb|Old Hungarian script
The Old Hungarian script was the writing system of the Hungarians. It was in use during the entire history of Hungary, albeit not as an official writing system. From the 19th century, it once again became more and more popular.
The Glagolitic alphabet was the initial script of the liturgical language Old Church Slavonic and became, together with the Greek uncial script, the basis of the Cyrillic script. Cyrillic is one of the most widely used modern alphabetic scripts and is notable for its use in Slavic languages and also for other languages within the former Soviet Union. Cyrillic alphabets include Serbian, Macedonian, Bulgarian, Russian, Belarusian, and Ukrainian. The Glagolitic alphabet is believed to have been created by Saints Cyril and Methodius, while the Cyrillic alphabet was created by a circle of their disciples in the Preslav Literary School including Naum of Preslav, Constantine of Preslav, Chernorizets Hrabar among others. They feature many letters that appear to have been borrowed from or influenced by Greek and Hebrew. |
Alphabet | Asian alphabets | Asian alphabets
Many phonetic scripts exist in Asia. The Arabic alphabet, Hebrew alphabet, Syriac alphabet, and other abjads of the Middle East are developments of the Aramaic alphabet.
Most alphabetic scripts of India and Eastern Asia descend from the Brahmi script, believed to be a descendant of Aramaic.
European alphabets, especially Latin and Cyrillic, have been adapted for many languages of Asia. Arabic is also widely used, sometimes as an abjad, as with Urdu and Persian, and sometimes as a complete alphabet, as with Kurdish and Uyghur.Thackston, W. M. (2006), "—Sorani Kurdish— A Reference Grammar with Selected Readings", Harvard Faculty of Arts & Sciences, Harvard University, retrieved 10 June 2021 |
Alphabet | Other alphabets | Other alphabets |
Alphabet | Hangul | Hangul
In Korea, Sejong the Great created the Hangul alphabet in 1443. Hangul is a unique alphabet: it is a featural alphabet, where the design of many of the letters comes from a sound's place of articulation, like P looking like the widened mouth and L looking like the tongue pulled in. The creation of Hangul was planned by the government of the day, and it places individual letters in syllable clusters with equal dimensions, in the same way as Chinese characters. This change allows for mixed-script writing, where one syllable always takes up one type space no matter how many letters get stacked into building that one sound-block. |
Alphabet | Bopomofo | Bopomofo
Bopomofo, also referred to as zhuyin, is a semi-syllabary used primarily in Taiwan to transcribe the sounds of Standard Chinese. Following the proclamation of the People's Republic of China in 1949 and its adoption of Hanyu Pinyin in 1956, the use of bopomofo on the mainland is limited. Bopomofo developed from a form of Chinese shorthand based on Chinese characters in the early 1900s and has elements of both an alphabet and a syllabary. Like an alphabet, the phonemes of syllable initials are represented by individual symbols, but like a syllabary, the phonemes of the syllable finals are not; each possible final (excluding the medial glide) has its own character, an example being luan written as ㄌㄨㄢ (l-u-an). The last symbol ㄢ takes place as the entire final -an. While bopomofo is not a mainstream writing system, it is still often used in ways similar to a romanization system, for aiding pronunciation and as an input method for Chinese characters on computers and cellphones. |
Alphabet | Types | Types
The term "alphabet" is used by linguists and paleographers in both a wide and a narrow sense. In a broader sense, an alphabet is a segmental script at the phoneme level—that is, it has separate glyphs for individual sounds and not for larger units such as syllables or words. In the narrower sense, some scholars distinguish "true" alphabets from two other types of segmental script, abjads, and abugidas. These three differ in how they treat vowels. Abjads have letters for consonants and leave most vowels unexpressed. Abugidas are also consonant-based but indicate vowels with diacritics, a systematic graphic modification of the consonants.For critics of the abjad-abugida-alphabet distinction, see , esp p. 22–27 The earliest known alphabet using this sense is the Wadi el-Hol script, believed to be an abjad. Its successor, Phoenician, is the ancestor of modern alphabets, including Arabic, Greek, Latin (via the Old Italic alphabet), Cyrillic (via the Greek alphabet), and Hebrew (via Aramaic).
left|thumb|263x263px|A Venn diagram showing the Greek (left), Cyrillic (bottom) and Latin (right) alphabets, which share many of the same letters, although they have different pronunciations
Examples of present-day abjads are the Arabic and Hebrew scripts; true alphabets include Latin, Cyrillic, and Korean hangul; and abugidas, used to write Tigrinya, Amharic, Hindi, and Thai. The Canadian Aboriginal syllabics are also an abugida, rather than a syllabary, as their name would imply, because each glyph stands for a consonant and is modified by rotation to represent the following vowel. In a true syllabary, each consonant-vowel combination gets represented by a separate glyph.Bernard Comrie, 2005, "Writing Systems", in Haspelmath et al. eds, The World Atlas of Language Structures (p 568 ff). Also Robert Bringhurst, 2004, The solid form of language: an essay on writing and meaning.
All three types may be augmented with syllabic glyphs. Ugaritic, for example, is essentially an abjad but has syllabic letters for Florian Coulmas, 1991, The writing systems of the world These are the only times that vowels are indicated. Coptic has a letter for . Devanagari is typically an abugida augmented with dedicated letters for initial vowels, though some traditions use अ as a zero consonant as the graphic base for such vowels.
The boundaries between the three types of segmental scripts are not always clear-cut. For example, Sorani Kurdish is written in the Arabic script, which, when used for other languages, is an abjad. In Kurdish, writing the vowels is mandatory, and whole letters are used, so the script is a true alphabet. Other languages may use a Semitic abjad with forced vowel diacritics, effectively making them abugidas. On the other hand, the ʼPhags-pa script of the Mongol Empire was based closely on the Tibetan abugida, but vowel marks are written after the preceding consonant rather than as diacritic marks. Although short a is not written, as in the Indic abugidas, The source of the term "abugida", namely the Geʽez script now used for Amharic and Tigrinya, has assimilated into their consonant modifications. It is no longer systematic and must be learned as a syllabary rather than as a segmental script. Even more extreme, the Pahlavi abjad eventually became logographic.
thumbnail|left|Geʽez script of Ethiopia and Eritrea
Thus the primary categorisation of alphabets reflects how they treat vowels. For tonal languages, further classification can be based on their treatment of tone. Though names do not yet exist to distinguish the various types. Some alphabets disregard tone entirely, especially when it does not carry a heavy functional load, as in Somali and many other languages of Africa and the Americas. Most commonly, tones are indicated by diacritics, which is how vowels are treated in abugidas, which is the case for Vietnamese (a true alphabet) and Thai (an abugida). In Thai, the tone is determined primarily by a consonant, with diacritics for disambiguation. In the Pollard script, an abugida, vowels are indicated by diacritics. The placing of the diacritic relative to the consonant is modified to indicate the tone. More rarely, a script may have separate letters for tones, as is the case for Hmong and Zhuang. For many, regardless of whether letters or diacritics get used, the most common tone is not marked, just as the most common vowel is not marked in Indic abugidas. In Zhuyin, not only is one of the tones unmarked; but there is a diacritic to indicate a lack of tone, like the virama of Indic. |
Alphabet | Alphabetical order | Alphabetical order
Alphabets often come to be associated with a standard ordering of their letters; this is for collation—namely, for listing words and other items in alphabetical order. |
Alphabet | Latin alphabets | Latin alphabets
The ordering of the Latin alphabet (A B C D E F G H I J K L M N O P Q R S T U V W X Y Z), which derives from the Northwest Semitic "Abgad" order, is already well established. Although, languages using this alphabet have different conventions for their treatment of modified letters (such as the French é, à, and ô) and certain combinations of letters (multigraphs). In French, these are not considered to be additional letters for collation. However, in Icelandic, the accented letters such as á, í, and ö are considered distinct letters representing different vowel sounds from sounds represented by their unaccented counterparts. In Spanish, ñ is considered a separate letter, but accented vowels such as á and é are not. The ll and ch were also formerly considered single letters and sorted separately after l and c, but in 1994, the tenth congress of the Association of Spanish Language Academies changed the collating order so that ll came to be sorted between lk and lm in the dictionary and ch came to be sorted between cg and ci; those digraphs were still formally designated as letters, but in 2010 the changed it, so they are no longer considered letters at all.Real Academia Española. Exclusión de «ch» y «ll» del abecedario."La 'i griega' se llamará 'ye'". Cuba Debate. 2010-11-05. Retrieved 12 December 2010. Cubadebate.cu
In German, words starting with sch- (which spells the German phoneme ) are inserted between words with initial sca- and sci- (all incidentally loanwords) instead of appearing after the initial sz, as though it were a single letter, which contrasts several languages such as Albanian, in which dh-, ë-, gj-, ll-, rr-, th-, xh-, and zh-, which all represent phonemes and considered separate single letters, would follow the letters respectively, as well as Hungarian and Welsh. Further, German words with an umlaut get collated ignoring the umlaut as—contrary to Turkish, which adopted the graphemes ö and ü, and where a word like tüfek would come after tuz, in the dictionary. An exception is the German telephone directory, where umlauts are sorted like ä=ae since names such as Jäger also appear with the spelling Jaeger and are not distinguished in the spoken language.
The Danish and Norwegian alphabets end with , whereas the Swedish conventionally put at the end. However, æ phonetically corresponds with , as does and . |
Alphabet | Early alphabets | Early alphabets
It is unknown whether the earliest alphabets had a defined sequence. Some alphabets today, such as the Hanuno'o script, are learned one letter at a time, in no particular order, and are not used for collation where a definite order is required. However, a dozen Ugaritic tablets from the 14th century BC preserve the alphabet in two sequences. One, the ABCDE order later used in Phoenician, has continued with minor changes in Hebrew, Greek, Armenian, Gothic, Cyrillic, and Latin; the other, HMĦLQ, was used in southern Arabia and is preserved today in Geʽez. Both orders have therefore been stable for at least 3000 years.
Runic used an unrelated Futhark sequence, which got simplified later on. Arabic usually uses its sequence, although Arabic retains the traditional abjadi order, which is used for numbers.
The Brahmic family of alphabets used in India uses a unique order based on phonology: The letters are arranged according to how and where the sounds get produced in the mouth. This organization is present in Southeast Asia, Tibet, Korean hangul, and even Japanese kana, which is not an alphabet. |
Alphabet | Acrophony | Acrophony
In Phoenician, each letter got associated with a word that begins with that sound. This is called acrophony and is continuously used to varying degrees in Samaritan, Aramaic, Syriac, Hebrew, Greek, and Arabic. Notice the "Names of the Letters" Section.
Acrophony was abandoned in Latin. It referred to the letters by adding a vowel—usually , sometimes or —before or after the consonant. Two exceptions were Y and Z, which were borrowed from the Greek alphabet rather than Etruscan. They were known as Y Graeca "Greek Y" and zeta (from Greek)—this discrepancy was inherited by many European languages, as in the term zed for Z in all forms of English, other than American English. Over time names sometimes shifted or were added, as in double U for W, or "double V" in French, the English name for Y, and the American zee for Z. Comparing them in English and French gives a clear reflection of the Great Vowel Shift: A, B, C, and D are pronounced in today's English, but in contemporary French they are . The French names (from which the English names got derived) preserve the qualities of the English vowels before the Great Vowel Shift. By contrast, the names of F, L, M, N, and S () remain the same in both languages because "short" vowels were largely unaffected by the Shift. Note how it says short vowels are similar between Middle and Modern English.
In Cyrillic, originally, acrophony was present using Slavic words. The first three words going, azŭ, buky, vědě, with the Cyrillic collation order being, А, Б, В. However, this was later abandoned in favor of a system similar to Latin. |
Alphabet | Orthography and pronunciation | Orthography and pronunciation
When an alphabet is adopted or developed to represent a given language, an orthography generally comes into being, providing rules for spelling words, following the principle on which alphabets get based. These rules will map letters of the alphabet to the phonemes of the spoken language. In a perfectly phonemic orthography, there would be a consistent one-to-one correspondence between the letters and the phonemes so that a writer could predict the spelling of a word given its pronunciation, and a speaker would always know the pronunciation of a word given its spelling, and vice versa. However, this ideal is usually never achieved in practice. Languages can come close to it, such as Spanish and Finnish. Others, such as English, deviate from it to a much larger degree.
The pronunciation of a language often evolves independently of its writing system. Writing systems have been borrowed for languages the orthography was not initially made to use. The degree to which letters of an alphabet correspond to phonemes of a language varies.
Languages may fail to achieve a one-to-one correspondence between letters and sounds in any of several ways:
A language may represent a given phoneme by combinations of letters rather than just a single letter. Two-letter combinations are called digraphs, and three-letter groups are called trigraphs. German uses the tetragraphs (four letters) "tsch" for the phoneme and (in a few borrowed words) "dsch" for . Kabardian also uses a tetragraph for one of its phonemes, namely "кхъу." Two letters representing one sound occur in several instances in Hungarian as well (where, for instance, cs stands for [tʃ], sz for [s], zs for [ʒ], dzs for [dʒ]).
A language may represent the same phoneme with two or more different letters or combinations of letters. An example is modern Greek which may write the phoneme in six different ways: , , , , , and .
A language may spell some words with unpronounced letters that exist for historical or other reasons. For example, the spelling of the Thai word for 'beer' retains a letter for the final consonant /r/ present in the English word it borrows, but silences it. Note in the pronunciation guide next to "เบียร์" it has it being said as, "Bia"
Pronunciation of individual words may change according to the presence of surrounding words in a sentence, for example, in sandhi.
Different dialects of a language may use different phonemes for the same word.
A language may use different sets of symbols or rules for distinct vocabulary items, typically for foreign words, such as in the Japanese katakana syllabary is used for foreign words, and there are rules in English for using loanwords from other languages.
National languages sometimes elect to address the problem of dialects by associating the alphabet with the national standard. Some national languages like Finnish, Armenian, Turkish, Russian, Serbo-Croatian (Serbian, Croatian, and Bosnian), and Bulgarian have a very regular spelling system with nearly one-to-one correspondence between letters and phonemes. Similarly, the Italian verb corresponding to 'spell (out),' compitare, is unknown to many Italians because spelling is usually trivial, as Italian spelling is highly phonemic. In standard Spanish, one can tell the pronunciation of a word from its spelling, but not vice versa, as phonemes sometimes can be represented in more than one way, but a given letter is consistently pronounced. French using silent letters, nasal vowels, and elision, may seem to lack much correspondence between the spelling and pronunciation. However, its rules on pronunciation, though complex, are consistent and predictable with a fair degree of accuracy.
At the other extreme are languages such as English, where pronunciations mostly have to be memorized as they do not correspond to the spelling consistently. For English, this is because the Great Vowel Shift occurred after the orthography got established and because English has acquired a large number of loanwords at different times, retaining their original spelling at varying levels. However, even English has general, albeit complex, rules that predict pronunciation from spelling. Rules like this are usually successful. However, rules to predict spelling from pronunciation have a higher failure rate.
Sometimes, countries have the written language undergo a spelling reform to realign the writing with the contemporary spoken language. These can range from simple spelling changes and word forms to switching the entire writing system. For example, Turkey switched from the Arabic alphabet to a Latin-based Turkish alphabet, and Kazakh changed from an Arabic script to a Cyrillic script due to the Soviet Union's influence. In 2021, it made a transition to the Latin alphabet, similar to Turkish.О переводе алфавита казахского языка с кириллицы на латинскую графику [On the change of the alphabet of the Kazakh language from the Cyrillic to the Latin script] (in Russian). President of the Republic of Kazakhstan. 26 October 2017. Archived from the original on 27 October 2017. Retrieved 26 October 2017. The Cyrillic script used to be official in Uzbekistan and Turkmenistan before they switched to the Latin alphabet. Uzbekistan is reforming the alphabet to use diacritics on the letters that are marked by apostrophes and the letters that are digraphs.
The standard system of symbols used by linguists to represent sounds in any language, independently of orthography, is called the International Phonetic Alphabet. |
Alphabet | See also | See also
Abecedarium
Alphabet book
Alphabet effect
Fingerspelling
Pangram
Letter symbolism |
Alphabet | References | References |
Alphabet | Bibliography | Bibliography
|
Alphabet | External links | External links
"Language, Writing and Alphabet: An Interview with Christophe Rico", Damqātum 3 (2007)
Michael Everson's Alphabets of Europe
How the Alphabet Was Born from Hieroglyphs—Biblical Archaeology Review
An Early Hellenic Alphabet
Museum of the Alphabet
The Alphabet, BBC Radio 4 discussion with Eleanor Robson, Alan Millard and Rosalind Thomas (In Our Time, 18 December 2003)
Category:Orthography |
Alphabet | Table of Content | Short description, Etymology, History, Alphabets related to Phoenician, Ancient Near Eastern alphabets, European alphabets, Asian alphabets, Other alphabets, Hangul, Bopomofo, Types, Alphabetical order, Latin alphabets, Early alphabets, Acrophony, Orthography and pronunciation, See also, References, Bibliography, External links |
Atomic number | Short description | thumb|300px|right|An explanation of the superscripts and subscripts seen in atomic number notation. Atomic number is the number of protons, and therefore also the total positive charge, in the atomic nucleus.
The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (np) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ordinary chemical elements. In an ordinary uncharged atom, the atomic number is also equal to the number of electrons.
For an ordinary atom which contains protons, neutrons and electrons, the sum of the atomic number Z and the neutron number N gives the atom's atomic mass number A. Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes) and the mass defect of the nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when expressed in daltons (making a quantity called the "relative isotopic mass"), is within 1% of the whole number A.
Atoms with the same atomic number but different neutron numbers, and hence different mass numbers, are known as isotopes. A little more than three-quarters of naturally occurring elements exist as a mixture of isotopes (see monoisotopic elements), and the average isotopic mass of an isotopic mixture for an element (called the relative atomic mass) in a defined environment on Earth determines the element's standard atomic weight. Historically, it was these atomic weights of elements (in comparison to hydrogen) that were the quantities measurable by chemists in the 19th century.
The conventional symbol Z comes from the German word 'number', which, before the modern synthesis of ideas from chemistry and physics, merely denoted an element's numerical place in the periodic table, whose order was then approximately, but not completely, consistent with the order of the elements by atomic weights. Only after 1915, with the suggestion and evidence that this Z number was also the nuclear charge and a physical characteristic of atoms, did the word (and its English equivalent atomic number) come into common use in this context.
The rules above do not always apply to exotic atoms which contain short-lived elementary particles other than protons, neutrons and electrons. |
Atomic number | History | History
In the 19th century, the term "atomic number" typically meant the number of atoms in a given volume.Leopold Gmelin (1848). Hand-book of Chemistry, p. 52: "...the specific gravity divided by the atomic weight gives the Atomic number, that is to say, the number of atoms in a given volume.James Curtis Booth, Campbell Morfit (1890). The Encyclopedia of Chemistry, Practical and Theoretical p.271: "The atomic number of a substance is its specific gravity, divided by its combining weight or equivalent. [...] the spec. grav. of a substance must be the number of atoms in a given volume, multiplied by their combining weight." Modern chemists prefer to use the concept of molar concentration.
In 1913, Antonius van den Broek proposed that the electric charge of an atomic nucleus, expressed as a multiplier of the elementary charge, was equal to the element's sequential position on the periodic table. Ernest Rutherford, in various articles in which he discussed van den Broek's idea, used the term "atomic number" to refer to an element's position on the periodic table. No writer before Rutherford is known to have used the term "atomic number" in this way, so it was probably he who established this definition.Eric Scerri (2020). The Periodic Table: Its Story and Its Significance, p. 185Helge Kragh (2012). Niels Bohr and the Quantum Atom, p. 33
After Rutherford deduced the existence of the proton in 1920, "atomic number" customarily referred to the proton number of an atom. In 1921, the German Atomic Weight Commission based its new periodic table on the nuclear charge number and in 1923 the International Committee on Chemical Elements followed suit.Helge Kragh (2012). Niels Bohr and the Quantum Atom, p. 34 |
Atomic number | The periodic table and a natural number for each element | The periodic table and a natural number for each element
thumb|upright|Russian chemist Dmitri Mendeleev, creator of the periodic table.
The periodic table of elements creates an ordering of the elements, and so they can be numbered in order.
Dmitri Mendeleev arranged his first periodic tables (first published on March 6, 1869) in order of atomic weight ("Atomgewicht").The Periodic Table of Elements , American Institute of Physics However, in consideration of the elements' observed chemical properties, he changed the order slightly and placed tellurium (atomic weight 127.6) ahead of iodine (atomic weight 126.9).The Development of the Periodic Table , Royal Society of Chemistry This placement is consistent with the modern practice of ordering the elements by proton number, Z, but that number was not known or suspected at the time.
A simple numbering based on atomic weight position was never entirely satisfactory. In addition to the case of iodine and tellurium, several other pairs of elements (such as argon and potassium, cobalt and nickel) were later shown to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not obvious, led to inconsistency and uncertainty in the periodic numbering of elements at least from lutetium (element 71) onward (hafnium was not known at this time). |
Atomic number | The Rutherford-Bohr model and van den Broek | The Rutherford-Bohr model and van den Broek
thumb|right|300px|The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model, it is an essential feature that the photon energy (or frequency) of the electromagnetic radiation emitted (shown) when an electron jumps from one orbital to another be proportional to the mathematical square of atomic charge (). Experimental measurements by Henry Moseley of this radiation for many elements (from ) showed the results as predicted by Bohr. Both the concept of atomic number and the Bohr model were thereby given scientific credence.
In 1911, Ernest Rutherford gave a model of the atom in which a central nucleus held most of the atom's mass and a positive charge which, in units of the electron's charge, was to be approximately equal to half of the atom's atomic weight, expressed in numbers of hydrogen atoms. This central charge would thus be approximately half the atomic weight (though it was almost 25% different from the atomic number of gold , ), the single element from which Rutherford made his guess). Nevertheless, in spite of Rutherford's estimation that gold had a central charge of about 100 (but was element on the periodic table), a month after Rutherford's paper appeared, Antonius van den Broek first formally suggested that the central charge and number of electrons in an atom were exactly equal to its place in the periodic table (also known as element number, atomic number, and symbolized Z). This eventually proved to be the case. |
Atomic number | Moseley's 1913 experiment | Moseley's 1913 experiment
thumb|upright|Henry Moseley in his lab.
The experimental position improved dramatically after research by Henry Moseley in 1913.Ordering the Elements in the Periodic Table , Royal Chemical Society Moseley, after discussions with Bohr who was at the same lab (and who had used Van den Broek's hypothesis in his Bohr model of the atom), decided to test Van den Broek's and Bohr's hypothesis directly, by seeing if spectral lines emitted from excited atoms fitted the Bohr theory's postulation that the frequency of the spectral lines be proportional to the square of Z.
To do this, Moseley measured the wavelengths of the innermost photon transitions (K and L lines) produced by the elements from aluminium (Z = 13) to gold (Z = 79) used as a series of movable anodic targets inside an x-ray tube. The square root of the frequency of these photons increased from one target to the next in an arithmetic progression. This led to the conclusion (Moseley's law) that the atomic number does closely correspond (with an offset of one unit for K-lines, in Moseley's work) to the calculated electric charge of the nucleus, i.e. the element number Z. Among other things, Moseley demonstrated that the lanthanide series (from lanthanum to lutetium inclusive) must have 15 members—no fewer and no more—which was far from obvious from known chemistry at that time. |
Atomic number | Missing elements | Missing elements
After Moseley's death in 1915, the atomic numbers of all known elements from hydrogen to uranium (Z = 92) were examined by his method. There were seven elements (with Z < 92) which were not found and therefore identified as still undiscovered, corresponding to atomic numbers 43, 61, 72, 75, 85, 87 and 91.Eric Scerri, A tale of seven elements, (Oxford University Press 2013) , p.47 From 1918 to 1947, all seven of these missing elements were discovered.Scerri chaps. 3–9 (one chapter per element) By this time, the first four transuranium elements had also been discovered, so that the periodic table was complete with no gaps as far as curium (Z = 96). |
Atomic number | The proton and the idea of nuclear electrons | The proton and the idea of nuclear electrons
In 1915, the reason for nuclear charge being quantized in units of Z, which were now recognized to be the same as the element number, was not understood. An old idea called Prout's hypothesis had postulated that the elements were all made of residues (or "protyles") of the lightest element hydrogen, which in the Bohr-Rutherford model had a single electron and a nuclear charge of one. However, as early as 1907, Rutherford and Thomas Royds had shown that alpha particles, which had a charge of +2, were the nuclei of helium atoms, which had a mass four times that of hydrogen, not two times. If Prout's hypothesis were true, something had to be neutralizing some of the charge of the hydrogen nuclei present in the nuclei of heavier atoms.
In 1917, Rutherford succeeded in generating hydrogen nuclei from a nuclear reaction between alpha particles and nitrogen gas,Ernest Rutherford | NZHistory.net.nz, New Zealand history online . Nzhistory.net.nz (19 October 1937). Retrieved on 2011-01-26. and believed he had proven Prout's law. He called the new heavy nuclear particles protons in 1920 (alternate names being proutons and protyles). It had been immediately apparent from the work of Moseley that the nuclei of heavy atoms have more than twice as much mass as would be expected from their being made of hydrogen nuclei, and thus there was required a hypothesis for the neutralization of the extra protons presumed present in all heavy nuclei. A helium nucleus was presumed to have four protons plus two "nuclear electrons" (electrons bound inside the nucleus) to cancel two charges. At the other end of the periodic table, a nucleus of gold with a mass 197 times that of hydrogen was thought to contain 118 nuclear electrons in the nucleus to give it a residual charge of +79, consistent with its atomic number. |
Atomic number | Discovery of the neutron makes ''Z'' the proton number | Discovery of the neutron makes Z the proton number
All consideration of nuclear electrons ended with James Chadwick's discovery of the neutron in 1932. An atom of gold now was seen as containing 118 neutrons rather than 118 nuclear electrons, and its positive nuclear charge now was realized to come entirely from a content of 79 protons. Since Moseley had previously shown that the atomic number Z of an element equals this positive charge, it was now clear that Z is identical to the number of protons of its nuclei. |
Atomic number | Chemical properties | Chemical properties
Each element has a specific set of chemical properties as a consequence of the number of electrons present in the neutral atom, which is Z (the atomic number). The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element's electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. Hence, it is the atomic number alone that determines the chemical properties of an element; and it is for this reason that an element can be defined as consisting of any mixture of atoms with a given atomic number. |
Atomic number | New elements | New elements
The quest for new elements is usually described using atomic numbers. As of , all elements with atomic numbers 1 to 118 have been observed. The most recent element discovered was number 117 (tennessine) in 2009. Synthesis of new elements is accomplished by bombarding target atoms of heavy elements with ions, such that the sum of the atomic numbers of the target and ion elements equals the atomic number of the element being created. In general, the half-life of a nuclide becomes shorter as atomic number increases, though undiscovered nuclides with certain "magic" numbers of protons and neutrons may have relatively longer half-lives and comprise an island of stability.
A hypothetical element composed only of neutrons, neutronium, has also been proposed and would have atomic number 0, but has never been observed. |
Atomic number | See also | See also
|
Atomic number | References | References
Category:Chemical properties
Category:Nuclear physics
Category:Atoms
Category:Dimensionless numbers of chemistry
Category:Numbers |
Atomic number | Table of Content | Short description, History, The periodic table and a natural number for each element, The Rutherford-Bohr model and van den Broek, Moseley's 1913 experiment, Missing elements, The proton and the idea of nuclear electrons, Discovery of the neutron makes ''Z'' the proton number, Chemical properties, New elements, See also, References |
Anatomy | short description | thumb|350px|One of the large, detailed illustrations in Andreas Vesalius's De humani corporis fabrica 16th century, marking the rebirth of anatomy
Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology, which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine, and is often studied alongside physiology.
Anatomy is a complex and dynamic field that is constantly evolving as discoveries are made. In recent years, there has been a significant increase in the use of advanced imaging techniques, such as MRI and CT scans, which allow for more detailed and accurate visualizations of the body's structures.
The discipline of anatomy is divided into macroscopic and microscopic parts. Macroscopic anatomy, or gross anatomy, is the examination of an animal's body parts using unaided eyesight. Gross anatomy also includes the branch of superficial anatomy. Microscopic anatomy involves the use of optical instruments in the study of the tissues of various structures, known as histology, and also in the study of cells.
The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of the human body. Methods have also improved dramatically, advancing from the examination of animals by dissection of carcasses and cadavers (corpses) to 20th-century medical imaging techniques, including X-ray, ultrasound, and magnetic resonance imaging. |
Anatomy | Etymology and definition | Etymology and definition
thumb|A dissected body, lying prone on a table, by Charles Landseer
Derived from the Greek anatomē "dissection" (from anatémnō "I cut up, cut open" from ἀνά aná "up", and τέμνω témnō "I cut"),O.D.E. 2nd edition 2005 anatomy is the scientific study of the structure of organisms including their systems, organs and tissues. It includes the appearance and position of the various parts, the materials from which they are composed, and their relationships with other parts. Anatomy is quite distinct from physiology and biochemistry, which deal respectively with the functions of those parts and the chemical processes involved. For example, an anatomist is concerned with the shape, size, position, structure, blood supply and innervation of an organ such as the liver; while a physiologist is interested in the production of bile, the role of the liver in nutrition and the regulation of bodily functions.
The discipline of anatomy can be subdivided into a number of branches, including gross or macroscopic anatomy and microscopic anatomy. Gross anatomy is the study of structures large enough to be seen with the naked eye, and also includes superficial anatomy or surface anatomy, the study by sight of the external body features. Microscopic anatomy is the study of structures on a microscopic scale, along with histology (the study of tissues), and embryology (the study of an organism in its immature condition). Regional anatomy is the study of the interrelationships of all of the structures in a specific body region, such as the abdomen. In contrast, systemic anatomy is the study of the structures that make up a discrete body system—that is, a group of structures that work together to perform a unique body function, such as the digestive system.
Anatomy can be studied using both invasive and non-invasive methods with the goal of obtaining information about the structure and organization of organs and systems. Methods used include dissection, in which a body is opened and its organs studied, and endoscopy, in which a video camera-equipped instrument is inserted through a small incision in the body wall and used to explore the internal organs and other structures. Angiography using X-rays or magnetic resonance angiography are methods to visualize blood vessels.
The term "anatomy" is commonly taken to refer to human anatomy. However, substantially similar structures and tissues are found throughout the rest of the animal kingdom, and the term also includes the anatomy of other animals. The term zootomy is also sometimes used to specifically refer to non-human animals. The structure and tissues of plants are of a dissimilar nature and they are studied in plant anatomy. |
Anatomy | Animal tissues | Animal tissues
right|thumb|Stylized cutaway diagram of an animal cell (with flagella)
The kingdom Animalia contains multicellular organisms that are heterotrophic and motile (although some have secondarily adopted a sessile lifestyle). Most animals have bodies differentiated into separate tissues and these animals are also known as eumetazoans. They have an internal digestive chamber, with one or two openings; the gametes are produced in multicellular sex organs, and the zygotes include a blastula stage in their embryonic development. Metazoans do not include the sponges, which have undifferentiated cells.
Unlike plant cells, animal cells have neither a cell wall nor chloroplasts. Vacuoles, when present, are more in number and much smaller than those in the plant cell. The body tissues are composed of numerous types of cells, including those found in muscles, nerves and skin. Each typically has a cell membrane formed of phospholipids, cytoplasm and a nucleus. All of the different cells of an animal are derived from the embryonic germ layers. Those simpler invertebrates which are formed from two germ layers of ectoderm and endoderm are called diploblastic and the more developed animals whose structures and organs are formed from three germ layers are called triploblastic. All of a triploblastic animal's tissues and organs are derived from the three germ layers of the embryo, the ectoderm, mesoderm and endoderm.
Animal tissues can be grouped into four basic types: connective, epithelial, muscle and nervous tissue.
thumb|Hyaline cartilage at high magnification (H&E stain) |
Anatomy | Connective tissue | Connective tissue
Connective tissues are fibrous and made up of cells scattered among inorganic material called the extracellular matrix. Often called fascia (from the Latin "fascia," meaning "band" or "bandage"), connective tissues give shape to organs and holds them in place. The main types are loose connective tissue, adipose tissue, fibrous connective tissue, cartilage and bone. The extracellular matrix contains proteins, the chief and most abundant of which is collagen. Collagen plays a major part in organizing and maintaining tissues. The matrix can be modified to form a skeleton to support or protect the body. An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization, as in crustaceans or by the cross-linking of its proteins as in insects. An endoskeleton is internal and present in all developed animals, as well as in many of those less developed. |
Anatomy | Epithelium | Epithelium
thumb|right|Gastric mucosa at low magnification (H&E stain)
Epithelial tissue is composed of closely packed cells, bound to each other by cell adhesion molecules, with little intercellular space. Epithelial cells can be squamous (flat), cuboidal or columnar and rest on a basal lamina, the upper layer of the basement membrane, the lower layer is the reticular lamina lying next to the connective tissue in the extracellular matrix secreted by the epithelial cells. There are many different types of epithelium, modified to suit a particular function. In the respiratory tract there is a type of ciliated epithelial lining; in the small intestine there are microvilli on the epithelial lining and in the large intestine there are intestinal villi. Skin consists of an outer layer of keratinized stratified squamous epithelium that covers the exterior of the vertebrate body. Keratinocytes make up to 95% of the cells in the skin.McGrath, J.A.; Eady, R.A.; Pope, F.M. (2004). Rook's Textbook of Dermatology (7th ed.). Blackwell Publishing. pp. 3.1–3.6. . The epithelial cells on the external surface of the body typically secrete an extracellular matrix in the form of a cuticle. In simple animals this may just be a coat of glycoproteins. In more advanced animals, many glands are formed of epithelial cells. |
Anatomy | Muscle tissue | Muscle tissue
right|thumb|Cross section through skeletal muscle and a small nerve at high magnification (H&E stain)
Muscle cells (myocytes) form the active contractile tissue of the body. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile filaments and is separated into three main types; smooth muscle, skeletal muscle and cardiac muscle. Smooth muscle has no striations when examined microscopically. It contracts slowly but maintains contractibility over a wide range of stretch lengths. It is found in such organs as sea anemone tentacles and the body wall of sea cucumbers. Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle is found in the walls of the uterus, bladder, intestines, stomach, oesophagus, respiratory airways, and blood vessels. Cardiac muscle is found only in the heart, allowing it to contract and pump blood round the body. |
Anatomy | Nervous tissue | Nervous tissue
Nervous tissue is composed of many nerve cells known as neurons which transmit information. In some slow-moving radially symmetrical marine animals such as ctenophores and cnidarians (including sea anemones and jellyfish), the nerves form a nerve net, but in most animals they are organized longitudinally into bundles. In simple animals, receptor neurons in the body wall cause a local reaction to a stimulus. In more complex animals, specialized receptor cells such as chemoreceptors and photoreceptors are found in groups and send messages along neural networks to other parts of the organism. Neurons can be connected together in ganglia. In higher animals, specialized receptors are the basis of sense organs and there is a central nervous system (brain and spinal cord) and a peripheral nervous system. The latter consists of sensory nerves that transmit information from sense organs and motor nerves that influence target organs. The peripheral nervous system is divided into the somatic nervous system which conveys sensation and controls voluntary muscle, and the autonomic nervous system which involuntarily controls smooth muscle, certain glands and internal organs, including the stomach. |
Anatomy | Vertebrate anatomy | Vertebrate anatomy
thumb|upright|Mouse skull. The neck and most of the forelimbs are also seen.
All vertebrates have a similar basic body plan and at some point in their lives, mostly in the embryonic stage, share the major chordate characteristics: a stiffening rod, the notochord; a dorsal hollow tube of nervous material, the neural tube; pharyngeal arches; and a tail posterior to the anus. The spinal cord is protected by the vertebral column and is above the notochord, and the gastrointestinal tract is below it. Nervous tissue is derived from the ectoderm, connective tissues are derived from mesoderm, and gut is derived from the endoderm. At the posterior end is a tail which continues the spinal cord and vertebrae but not the gut. The mouth is found at the anterior end of the animal, and the anus at the base of the tail. The defining characteristic of a vertebrate is the vertebral column, formed in the development of the segmented series of vertebrae. In most vertebrates the notochord becomes the nucleus pulposus of the intervertebral discs. However, a few vertebrates, such as the sturgeon and the coelacanth, retain the notochord into adulthood. Jawed vertebrates are typified by paired appendages, fins or legs, which may be secondarily lost. The limbs of vertebrates are considered to be homologous because the same underlying skeletal structure was inherited from their last common ancestor. This is one of the arguments put forward by Charles Darwin to support his theory of evolution. |
Anatomy | Fish anatomy | Fish anatomy
thumb|left|Cutaway diagram showing various organs of a fish
The body of a fish is divided into a head, trunk and tail, although the divisions between the three are not always externally visible. The skeleton, which forms the support structure inside the fish, is either made of cartilage, in cartilaginous fish, or bone in bony fish. The main skeletal element is the vertebral column, composed of articulating vertebrae which are lightweight yet strong. The ribs attach to the spine and there are no limbs or limb girdles. The main external features of the fish, the fins, are composed of either bony or soft spines called rays, which with the exception of the caudal fins, have no direct connection with the spine. They are supported by the muscles which compose the main part of the trunk. The heart has two chambers and pumps the blood through the respiratory surfaces of the gills and on round the body in a single circulatory loop. The eyes are adapted for seeing underwater and have only local vision. There is an inner ear but no external or middle ear. Low frequency vibrations are detected by the lateral line system of sense organs that run along the length of the sides of fish, and these respond to nearby movements and to changes in water pressure.
Sharks and rays are basal fish with numerous primitive anatomical features similar to those of ancient fish, including skeletons composed of cartilage. Their bodies tend to be dorso-ventrally flattened, they usually have five pairs of gill slits and a large mouth set on the underside of the head. The dermis is covered with separate dermal placoid scales. They have a cloaca into which the urinary and genital passages open, but not a swim bladder. Cartilaginous fish produce a small number of large, yolky eggs. Some species are ovoviviparous and the young develop internally but others are oviparous and the larvae develop externally in egg cases.
The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from the features of ancient fish. They have a bony skeleton, are generally laterally flattened, have five pairs of gills protected by an operculum, and a mouth at or near the tip of the snout. The dermis is covered with overlapping scales. Bony fish have a swim bladder which helps them maintain a constant depth in the water column, but not a cloaca. They mostly spawn a large number of small eggs with little yolk which they broadcast into the water column. |
Anatomy | Amphibian anatomy | Amphibian anatomy
thumb|left|alt=Frog skeleton|Skeleton of Surinam horned frog (Ceratophrys cornuta)
thumb|upright|Plastic model of a frog
Amphibians are a class of animals comprising frogs, salamanders and caecilians. They are tetrapods, but the caecilians and a few species of salamander have either no limbs or their limbs are much reduced in size. Their main bones are hollow and lightweight and are fully ossified and the vertebrae interlock with each other and have articular processes. Their ribs are usually short and may be fused to the vertebrae. Their skulls are mostly broad and short, and are often incompletely ossified. Their skin contains little keratin and lacks scales, but contains many mucous glands and in some species, poison glands. The hearts of amphibians have three chambers, two atria and one ventricle. They have a urinary bladder and nitrogenous waste products are excreted primarily as urea. Amphibians breathe by means of buccal pumping, a pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin which needs to be kept moist.
In frogs the pelvic girdle is robust and the hind legs are much longer and stronger than the forelimbs. The feet have four or five digits and the toes are often webbed for swimming or have suction pads for climbing. Frogs have large eyes and no tail. Salamanders resemble lizards in appearance; their short legs project sideways, the belly is close to or in contact with the ground and they have a long tail. Caecilians superficially resemble earthworms and are limbless. They burrow by means of zones of muscle contractions which move along the body and they swim by undulating their body from side to side. |
Anatomy | Reptile anatomy | Reptile anatomy
thumb|left|Skeleton of a western diamondback rattlesnake
Reptiles are a class of animals comprising turtles, tuataras, lizards, snakes and crocodiles. They are tetrapods, but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. The teeth are conical and mostly uniform in size. The surface cells of the epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with a copulatory organ present in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder is small as nitrogenous waste is excreted as uric acid.
Turtles are notable for their protective shells. They have an inflexible trunk encased in a horny carapace above and a plastron below. These are formed from bony plates embedded in the dermis which are overlain by horny ones and are partially fused with the ribs and spine. The neck is long and flexible and the head and the legs can be drawn back inside the shell. Turtles are vegetarians and the typical reptile teeth have been replaced by sharp, horny plates. In aquatic species, the front legs are modified into flippers.
Tuataras superficially resemble lizards but the lineages diverged in the Triassic period. There is one living species, Sphenodon punctatus. The skull has two openings (fenestrae) on either side and the jaw is rigidly attached to the skull. There is one row of teeth in the lower jaw and this fits between the two rows in the upper jaw when the animal chews. The teeth are merely projections of bony material from the jaw and eventually wear down. The brain and heart are more primitive than those of other reptiles, and the lungs have a single chamber and lack bronchi. The tuatara has a well-developed parietal eye on its forehead.
Lizards have skulls with only one fenestra on each side, the lower bar of bone below the second fenestra having been lost. This results in the jaws being less rigidly attached which allows the mouth to open wider. Lizards are mostly quadrupeds, with the trunk held off the ground by short, sideways-facing legs, but a few species have no limbs and resemble snakes. Lizards have moveable eyelids, eardrums are present and some species have a central parietal eye.
Snakes are closely related to lizards, having branched off from a common ancestral lineage during the Cretaceous period, and they share many of the same features. The skeleton consists of a skull, a hyoid bone, spine and ribs though a few species retain a vestige of the pelvis and rear limbs in the form of pelvic spurs. The bar under the second fenestra has also been lost and the jaws have extreme flexibility allowing the snake to swallow its prey whole. Snakes lack moveable eyelids, the eyes being covered by transparent "spectacle" scales. They do not have eardrums but can detect ground vibrations through the bones of their skull. Their forked tongues are used as organs of taste and smell and some species have sensory pits on their heads enabling them to locate warm-blooded prey.
Crocodilians are large, low-slung aquatic reptiles with long snouts and large numbers of teeth. The head and trunk are dorso-ventrally flattened and the tail is laterally compressed. It undulates from side to side to force the animal through the water when swimming. The tough keratinized scales provide body armour and some are fused to the skull. The nostrils, eyes and ears are elevated above the top of the flat head enabling them to remain above the surface of the water when the animal is floating. Valves seal the nostrils and ears when it is submerged. Unlike other reptiles, crocodilians have hearts with four chambers allowing complete separation of oxygenated and deoxygenated blood. |
Anatomy | Bird anatomy | Bird anatomy
thumb|Part of a wing. Albrecht Dürer,
Birds are tetrapods but though their hind limbs are used for walking or hopping, their front limbs are wings covered with feathers and adapted for flight. Birds are endothermic, have a high metabolic rate, a light skeletal system and powerful muscles. The long bones are thin, hollow and very light. Air sac extensions from the lungs occupy the centre of some bones. The sternum is wide and usually has a keel and the caudal vertebrae are fused. There are no teeth and the narrow jaws are adapted into a horn-covered beak. The eyes are relatively large, particularly in nocturnal species such as owls. They face forwards in predators and sideways in ducks.
The feathers are outgrowths of the epidermis and are found in localized bands from where they fan out over the skin. Large flight feathers are found on the wings and tail, contour feathers cover the bird's surface and fine down occurs on young birds and under the contour feathers of water birds. The only cutaneous gland is the single uropygial gland near the base of the tail. This produces an oily secretion that waterproofs the feathers when the bird preens. There are scales on the legs, feet and claws on the tips of the toes. |
Anatomy | Mammal anatomy | Mammal anatomy
Mammals are a diverse class of animals, mostly terrestrial but some are aquatic and others have evolved flapping or gliding flight. They mostly have four limbs, but some aquatic mammals have no limbs or limbs modified into fins, and the forelimbs of bats are modified into wings. The legs of most mammals are situated below the trunk, which is held well clear of the ground. The bones of mammals are well ossified and their teeth, which are usually differentiated, are coated in a layer of prismatic enamel. The teeth are shed once (milk teeth) during the animal's lifetime or not at all, as is the case in cetaceans. Mammals have three bones in the middle ear and a cochlea in the inner ear. They are clothed in hair and their skin contains glands which secrete sweat. Some of these glands are specialized as mammary glands, producing milk to feed the young. Mammals breathe with lungs and have a muscular diaphragm separating the thorax from the abdomen which helps them draw air into the lungs. The mammalian heart has four chambers, and oxygenated and deoxygenated blood are kept entirely separate. Nitrogenous waste is excreted primarily as urea.
Mammals are amniotes, and most are viviparous, giving birth to live young. Exceptions to this are the egg-laying monotremes, the platypus and the echidnas of Australia. Most other mammals have a placenta through which the developing foetus obtains nourishment, but in marsupials, the foetal stage is very short and the immature young is born and finds its way to its mother's pouch where it latches on to a teat and completes its development. |
Anatomy | Human anatomy | Human anatomy
thumb|left|Sagittal sections of the head as seen by a modern MRI scan
upright|thumb|In humans, dexterous hand movements and increased brain size are likely to have evolved simultaneously.
Humans have the overall body plan of a mammal. Humans have a head, neck, trunk (which includes the thorax and abdomen), two arms and hands, and two legs and feet.
Generally, students of certain biological sciences, paramedics, prosthetists and orthotists, physiotherapists, occupational therapists, nurses, podiatrists, and medical students learn gross anatomy and microscopic anatomy from anatomical models, skeletons, textbooks, diagrams, photographs, lectures and tutorials and in addition, medical students generally also learn gross anatomy through practical experience of dissection and inspection of cadavers. The study of microscopic anatomy (or histology) can be aided by practical experience examining histological preparations (or slides) under a microscope.
Human anatomy, physiology and biochemistry are complementary basic medical sciences, which are generally taught to medical students in their first year at medical school. Human anatomy can be taught regionally or systemically; that is, respectively, studying anatomy by bodily regions such as the head and chest, or studying by specific systems, such as the nervous or respiratory systems. The major anatomy textbook, Gray's Anatomy, has been reorganized from a systems format to a regional format, in line with modern teaching methods. A thorough working knowledge of anatomy is required by physicians, especially surgeons and doctors working in some diagnostic specialties, such as histopathology and radiology.
Academic anatomists are usually employed by universities, medical schools or teaching hospitals. They are often involved in teaching anatomy, and research into certain systems, organs, tissues or cells. |
Anatomy | Invertebrate anatomy | Invertebrate anatomy
thumb|Head of a male Daphnia, a planktonic crustacean
Invertebrates constitute a vast array of living organisms ranging from the simplest unicellular eukaryotes such as Paramecium to such complex multicellular animals as the octopus, lobster and dragonfly. They constitute about 95% of the animal species. By definition, none of these creatures has a backbone. The cells of single-cell protozoans have the same basic structure as those of multicellular animals but some parts are specialized into the equivalent of tissues and organs. Locomotion is often provided by cilia or flagella or may proceed via the advance of pseudopodia, food may be gathered by phagocytosis, energy needs may be supplied by photosynthesis and the cell may be supported by an endoskeleton or an exoskeleton. Some protozoans can form multicellular colonies.
Metazoans are a multicellular organism, with different groups of cells serving different functions. The most basic types of metazoan tissues are epithelium and connective tissue, both of which are present in nearly all invertebrates. The outer surface of the epidermis is normally formed of epithelial cells and secretes an extracellular matrix which provides support to the organism. An endoskeleton derived from the mesoderm is present in echinoderms, sponges and some cephalopods. Exoskeletons are derived from the epidermis and is composed of chitin in arthropods (insects, spiders, ticks, shrimps, crabs, lobsters). Calcium carbonate constitutes the shells of molluscs, brachiopods and some tube-building polychaete worms and silica forms the exoskeleton of the microscopic diatoms and radiolaria. Other invertebrates may have no rigid structures but the epidermis may secrete a variety of surface coatings such as the pinacoderm of sponges, the gelatinous cuticle of cnidarians (polyps, sea anemones, jellyfish) and the collagenous cuticle of annelids. The outer epithelial layer may include cells of several types including sensory cells, gland cells and stinging cells. There may also be protrusions such as microvilli, cilia, bristles, spines and tubercles.
Marcello Malpighi, the father of microscopical anatomy, discovered that plants had tubules similar to those he saw in insects like the silk worm. He observed that when a ring-like portion of bark was removed on a trunk a swelling occurred in the tissues above the ring, and he unmistakably interpreted this as growth stimulated by food coming down from the leaves, and being captured above the ring. |
Anatomy | Arthropod anatomy | Arthropod anatomy
Arthropods comprise the largest phylum of invertebrates in the animal kingdom with over a million known species.Britannica Concise Encyclopaedia 2007
Insects possess segmented bodies supported by a hard-jointed outer covering, the exoskeleton, made mostly of chitin. The segments of the body are organized into three distinct parts, a head, a thorax and an abdomen. The head typically bears a pair of sensory antennae, a pair of compound eyes, one to three simple eyes (ocelli) and three sets of modified appendages that form the mouthparts. The thorax has three pairs of segmented legs, one pair each for the three segments that compose the thorax and one or two pairs of wings. The abdomen is composed of eleven segments, some of which may be fused and houses the digestive, respiratory, excretory and reproductive systems. There is considerable variation between species and many adaptations to the body parts, especially wings, legs, antennae and mouthparts.
Spiders a class of arachnids have four pairs of legs; a body of two segments—a cephalothorax and an abdomen. Spiders have no wings and no antennae. They have mouthparts called chelicerae which are often connected to venom glands as most spiders are venomous. They have a second pair of appendages called pedipalps attached to the cephalothorax. These have similar segmentation to the legs and function as taste and smell organs. At the end of each male pedipalp is a spoon-shaped cymbium that acts to support the copulatory organ. |
Anatomy | Other branches of anatomy | Other branches of anatomy
Surface anatomy is important as the study of anatomical landmarks that can be readily seen from the exterior contours of the body. It enables medics and veterinarians to gauge the position and anatomy of the associated deeper structures. Superficial is a directional term that indicates that structures are located relatively close to the surface of the body.
Comparative anatomy relates to the comparison of anatomical structures (both gross and microscopic) in different animals.
Artistic anatomy relates to anatomic studies of body proportions for artistic reasons. |
Anatomy | History | History |
Anatomy | Ancient | Ancient
thumb|upright=1.05|Image of early rendition of anatomy findings
In 1600 BCE, the Edwin Smith Papyrus, an Ancient Egyptian medical text, described the heart and its vessels, as well as the brain and its meninges and cerebrospinal fluid, and the liver, spleen, kidneys, uterus and bladder. It showed the blood vessels diverging from the heart. The Ebers Papyrus () features a "treatise on the heart", with vessels carrying all the body's fluids to or from every member of the body.
Ancient Greek anatomy and physiology underwent great changes and advances throughout the early medieval world. Over time, this medical practice expanded due to a continually developing understanding of the functions of organs and structures in the body. Phenomenal anatomical observations of the human body were made, which contributed to the understanding of the brain, eye, liver, reproductive organs, and nervous system.
The Hellenistic Egyptian city of Alexandria was the stepping-stone for Greek anatomy and physiology. Alexandria not only housed the biggest library for medical records and books of the liberal arts in the world during the time of the Greeks but was also home to many medical practitioners and philosophers. Great patronage of the arts and sciences from the Ptolemaic dynasty of Egypt helped raise Alexandria up, further rivalling other Greek states' cultural and scientific achievements.
thumb|An anatomy thangka, part of Desi Sangye Gyatso's The Blue Beryl, 17th century
Some of the most striking advances in early anatomy and physiology took place in Hellenistic Alexandria. Two of the most famous anatomists and physiologists of the third century were Herophilus and Erasistratus. These two physicians helped pioneer human dissection for medical research, using the cadavers of condemned criminals, which was considered taboo until the Renaissance—Herophilus was recognized as the first person to perform systematic dissections. Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine. Some of the works included classifying the system of the pulse, the discovery that human arteries had thicker walls than veins, and that the atria were parts of the heart. Herophilus's knowledge of the human body has provided vital input towards understanding the brain, eye, liver, reproductive organs, and nervous system and characterizing the course of the disease. Erasistratus accurately described the structure of the brain, including the cavities and membranes, and made a distinction between its cerebrum and cerebellum During his study in Alexandria, Erasistratus was particularly concerned with studies of the circulatory and nervous systems. He could distinguish the human body's sensory and motor nerves and believed air entered the lungs and heart, which was then carried throughout the body. His distinction between the arteries and veins—the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery. Erasistratus was also responsible for naming and describing the function of the epiglottis and the heart's valves, including the tricuspid. During the third century, Greek physicians were able to differentiate nerves from blood vessels and tendons and to realize that the nerves convey neural impulses. It was Herophilus who made the point that damage to motor nerves induced paralysis. Herophilus named the meninges and ventricles in the brain, appreciated the division between cerebellum and cerebrum and recognized that the brain was the "seat of intellect" and not a "cooling chamber" as propounded by Aristotle Herophilus is also credited with describing the optic, oculomotor, motor division of the trigeminal, facial, vestibulocochlear and hypoglossal nerves.
200px|thumb|right|Surgical instruments were invented by Abulcasis in the 11th century
200px|thumb|left|Anatomy of the eye for the first time in history by Hunayn ibn Ishaq in the 9th century
thumb|13th century anatomical illustration
Incredible feats were made during the third century BCE in both the digestive and reproductive systems. Herophilus discovered and described not only the salivary glands but also the small intestine and liver. He showed that the uterus is a hollow organ and described the ovaries and uterine tubes. He recognized that spermatozoa were produced by the testes and was the first to identify the prostate gland.
The anatomy of the muscles and skeleton is described in the Hippocratic Corpus, an Ancient Greek medical work written by unknown authors. Aristotle described vertebrate anatomy based on animal dissection. Praxagoras identified the difference between arteries and veins. Also in the 4th century BCE, Herophilos and Erasistratus produced more accurate anatomical descriptions based on vivisection of criminals in Alexandria during the Ptolemaic period."Alexandrian Medicine" . Antiqua Medicina – from Homer to Vesalius. University of Virginia.
In the 2nd century, Galen of Pergamum, an anatomist, clinician, writer, and philosopher, wrote the final and highly influential anatomy treatise of ancient times. He compiled existing knowledge and studied anatomy through the dissection of animals. He was one of the first experimental physiologists through his vivisection experiments on animals.Brock, Arthur John (translator) Galen. On the Natural Faculties. Edinburgh, 1916. Introduction, page xxxiii. Galen's drawings, based mostly on dog anatomy, became effectively the only anatomical textbook for the next thousand years. His work was known to Renaissance doctors only through Islamic Golden Age medicine until it was translated from Greek sometime in the 15th century. |
Anatomy | Medieval to early modern | Medieval to early modern
left|thumb|Anatomical study of the arm, by Leonardo da Vinci, (about 1510)
thumb|upright|Anatomical chart in Vesalius's Epitome, 1543
thumb|right|Michiel Jansz van Mierevelt – Anatomy lesson of Dr. Willem van der Meer, 1617
Anatomy developed little from classical times until the sixteenth century; as the historian Marie Boas writes, "Progress in anatomy before the sixteenth century is as mysteriously slow as its development after 1500 is startlingly rapid". Between 1275 and 1326, the anatomists Mondino de Luzzi, Alessandro Achillini and Antonio Benivieni at Bologna carried out the first systematic human dissections since ancient times. Mondino's Anatomy of 1316 was the first textbook in the medieval rediscovery of human anatomy. It describes the body in the order followed in Mondino's dissections, starting with the abdomen, thorax, head, and limbs. It was the standard anatomy textbook for the next century.
Leonardo da Vinci (1452–1519) was trained in anatomy by Andrea del Verrocchio. He made use of his anatomical knowledge in his artwork, making many sketches of skeletal structures, muscles and organs of humans and other vertebrates that he dissected.
Andreas Vesalius (1514–1564), professor of anatomy at the University of Padua, is considered the founder of modern human anatomy. Originally from Brabant, Vesalius published the influential book De humani corporis fabrica ("the structure of the human body"), a large format book in seven volumes, in 1543.Vesalius, Andreas. De humani corporis fabrica libri septem. Basileae [Basel]: Ex officina Joannis Oporini, 1543. The accurate and intricately detailed illustrations, often in allegorical poses against Italianate landscapes, are thought to have been made by the artist Jan van Calcar, a pupil of Titian.O'Malley, C.D. Andreas Vesalius of Brussels, 1514–1564. Berkeley: University of California Press, 1964.
In England, anatomy was the subject of the first public lectures given in any science; these were provided by the Company of Barbers and Surgeons in the 16th century, joined in 1583 by the Lumleian lectures in surgery at the Royal College of Physicians. |
Anatomy | Late modern | Late modern
left|thumb|Anatomy teaching with female students, 1891–1893
Medical schools began to be set up in the United States towards the end of the 18th century. Classes in anatomy needed a continual stream of cadavers for dissection, and these were difficult to obtain. Philadelphia, Baltimore, and New York were all renowned for body snatching activity as criminals raided graveyards at night, removing newly buried corpses from their coffins. A similar problem existed in Britain where demand for bodies became so great that grave-raiding and even anatomy murder were practised to obtain cadavers.Rosner, Lisa. 2010. The Anatomy Murders. Being the True and Spectacular History of Edinburgh's Notorious Burke and Hare and of the Man of Science Who Abetted Them in the Commission of Their Most Heinous Crimes. University of Pennsylvania Press Some graveyards were, in consequence, protected with watchtowers. The practice was halted in Britain by the Anatomy Act of 1832, while in the United States, similar legislation was enacted after the physician William S. Forbes of Jefferson Medical College was found guilty in 1882 of "complicity with resurrectionists in the despoliation of graves in Lebanon Cemetery".
The teaching of anatomy in Britain was transformed by Sir John Struthers, Regius Professor of Anatomy at the University of Aberdeen from 1863 to 1889. He was responsible for setting up the system of three years of "pre-clinical" academic teaching in the sciences underlying medicine, including especially anatomy. This system lasted until the reform of medical training in 1993 and 2003. As well as teaching, he collected many vertebrate skeletons for his museum of comparative anatomy, published over 70 research papers, and became famous for his public dissection of the Tay Whale. From 1822 the Royal College of Surgeons regulated the teaching of anatomy in medical schools. Medical museums provided examples in comparative anatomy, and were often used in teaching. Ignaz Semmelweis investigated puerperal fever and he discovered how it was caused. He noticed that the frequently fatal fever occurred more often in mothers examined by medical students than by midwives. The students went from the dissecting room to the hospital ward and examined women in childbirth. Semmelweis showed that when the trainees washed their hands in chlorinated lime before each clinical examination, the incidence of puerperal fever among the mothers could be reduced dramatically.
upright|thumb|An electron microscope from 1973
Before the modern medical era, the primary means for studying the internal structures of the body were dissection of the dead and inspection, palpation, and auscultation of the living. The advent of microscopy opened up an understanding of the building blocks that constituted living tissues. Technical advances in the development of achromatic lenses increased the resolving power of the microscope, and around 1839, Matthias Jakob Schleiden and Theodor Schwann identified that cells were the fundamental unit of organization of all living things. The study of small structures involved passing light through them, and the microtome was invented to provide sufficiently thin slices of tissue to examine. Staining techniques using artificial dyes were established to help distinguish between different tissue types. Advances in the fields of histology and cytology began in the late 19th century along with advances in surgical techniques allowing for the painless and safe removal of biopsy specimens. The invention of the electron microscope brought a significant advance in resolution power and allowed research into the ultrastructure of cells and the organelles and other structures within them. About the same time, in the 1950s, the use of X-ray diffraction for studying the crystal structures of proteins, nucleic acids, and other biological molecules gave rise to a new field of molecular anatomy.
Equally important advances have occurred in non-invasive techniques for examining the body's interior structures. X-rays can be passed through the body and used in medical radiography and fluoroscopy to differentiate interior structures that have varying degrees of opaqueness. Magnetic resonance imaging, computed tomography, and ultrasound imaging have all enabled the examination of internal structures in unprecedented detail to a degree far beyond the imagination of earlier generations. |
Anatomy | See also | See also
Anatomical model
Outline of human anatomy
Plastination
Evelyn tables
|
Anatomy | References | References |
Anatomy | External links | External links
Anatomy, In Our Time. BBC Radio 4. Melvyn Bragg with guests Ruth Richardson, Andrew Cunningham and Harold Ellis.
"Anatomy of the Human Body". 20th edition. 1918. Henry Gray
Anatomia Collection: anatomical plates 1522 to 1867 (digitized books and images)
Lyman, Henry Munson. The Book of Health (1898). Science History Institute Digital Collections .
Gunther von Hagens True Anatomy for New Ways of Teaching. |
Anatomy | Sources | Sources
Category:Anatomical terminology
Category:Branches of biology
Category:Morphology (biology) |
Anatomy | Table of Content | short description, Etymology and definition, Animal tissues, Connective tissue, Epithelium, Muscle tissue, Nervous tissue, Vertebrate anatomy, Fish anatomy, Amphibian anatomy, Reptile anatomy, Bird anatomy, Mammal anatomy, Human anatomy, Invertebrate anatomy, Arthropod anatomy, Other branches of anatomy, History, Ancient, Medieval to early modern, Late modern, See also, References, External links, Sources |
Affirming the consequent | Short description | In propositional logic, affirming the consequent (also known as converse error, fallacy of the converse, or confusion of necessity and sufficiency) is a formal fallacy (or an invalid form of argument) that is committed when, in the context of an indicative conditional statement, it is stated that because the consequent is true, therefore the antecedent is true. It takes on the following form:
If P, then Q.
Q.
Therefore, P.
which may also be phrased as
(P implies Q)
(therefore, Q implies P)
For example, it may be true that a broken lamp would cause a room to become dark. It is not true, however, that a dark room implies the presence of a broken lamp. There may be no lamp (or any light source). The lamp may also be off. In other words, the consequent (a dark room) can have other antecedents (no lamp, off-lamp), and so can still be true even if the stated antecedent is not.
Converse errors are common in everyday thinking and communication and can result from, among other causes, communication issues, misconceptions about logic, and failure to consider other causes.
A related fallacy is denying the antecedent. Two related valid forms of logical argument include modus tollens (denying the consequent) and modus ponens (affirming the antecedent). |
Affirming the consequent | Formal description | Formal description
Affirming the consequent is the action of taking a true statement and invalidly concluding its converse . The name affirming the consequent derives from using the consequent, Q, of , to conclude the antecedent P. This fallacy can be summarized formally as or, alternatively, .Hurley, Patrick J. (2010), A Concise Introduction to Logic (11th edition). Wadsworth Cengage Learning, pp. 362–63.
The root cause of such a logical error is sometimes failure to realize that just because P is a possible condition for Q, P may not be the only condition for Q, i.e. Q may follow from another condition as well.
Affirming the consequent can also result from overgeneralizing the experience of many statements having true converses. If P and Q are "equivalent" statements, i.e. , it is possible to infer P under the condition Q. For example, the statements "It is August 13, so it is my birthday" and "It is my birthday, so it is August 13" are equivalent and both true consequences of the statement "August 13 is my birthday" (an abbreviated form of ).
Of the possible forms of "mixed hypothetical syllogisms," two are valid and two are invalid. Affirming the antecedent (modus ponens) and denying the consequent (modus tollens) are valid. Affirming the consequent and denying the antecedent are invalid.Kelley, David (1998), The Art of Reasoning (3rd edition). Norton, pp. 290–94. |
Affirming the consequent | Additional examples | Additional examples
Example 1
One way to demonstrate the invalidity of this argument form is with a counterexample with true premises but an obviously false conclusion. For example:
If someone lives in San Diego, then they live in California.
Joe lives in California.
Therefore, Joe lives in San Diego.
There are many places to live in California other than San Diego. On the other hand, one can affirm with certainty that "if someone does not live in California" (non-Q), then "this person does not live in San Diego" (non-P). This is the contrapositive of the first statement, and it must be true if and only if the original statement is true.
Example 2
If an animal is a dog, then it has four legs.
My cat has four legs.
Therefore, my cat is a dog.
Here, it is immediately intuitive that any number of other antecedents ("If an animal is a deer...", "If an animal is an elephant...", "If an animal is a moose...", etc.) can give rise to the consequent ("then it has four legs"), and that it is preposterous to suppose that having four legs must imply that the animal is a dog and nothing else. This is useful as a teaching example since most people can immediately recognize that the conclusion reached must be wrong (intuitively, a cat cannot be a dog), and that the method by which it was reached must therefore be fallacious. This argument was featured in Euguene Ionesco's Rhinoceros in a conversation between a Logician and an Old Gentleman.
Example 3
In Catch-22, the chaplain is interrogated for supposedly being "Washington Irving"/"Irving Washington", who has been blocking out large portions of soldiers' letters home. The colonel has found such a letter, but with the chaplain's name signed.
"You can read, though, can't you?" the colonel persevered sarcastically. "The author signed his name."
"That's my name there."
"Then you wrote it. Q.E.D."
P in this case is 'The chaplain signs his own name', and Q 'The chaplain's name is written'. The chaplain's name may be written, but he did not necessarily write it, as the colonel falsely concludes.See also
Abductive reasoning
Appeal to consequences
Confusion of the inverse
Denying the antecedent
Fallacies of illicit transference
Fallacy of the single cause
Fallacy of the undistributed middle
Modus ponens Modus tollens Necessity and sufficiency
Post hoc ergo propter hoc'' |
Affirming the consequent | References | References
Category:Formal fallacies |
Affirming the consequent | Table of Content | Short description, Formal description, Additional examples, References |
Andrei Tarkovsky | Short description | Andrei Arsenyevich Tarkovsky (, ; 4 April 1932 // Большая российская энциклопедия. Том 31. Москва, 2016, с. 674. – 29 December 1986) was a Soviet film director and screenwriter of Russian origin. He is widely considered one of the greatest directors in cinema history. His films explore spiritual and metaphysical themes and are known for their slow pacing and long takes, dreamlike visual imagery and preoccupation with nature and memory.
Tarkovsky studied film at the All-Union State Institute of Cinematography under filmmaker Mikhail Romm and subsequently directed his first five features in the Soviet Union: Ivan's Childhood (1962), Andrei Rublev (1966), Solaris (1972), Mirror (1975), and Stalker (1979). After years of creative conflict with state film authorities, he left the country in 1979 and made his final two films—Nostalghia (1983) and The Sacrifice (1986)—abroad. In 1986, he published Sculpting in Time, a book about cinema and art. He died later that year of cancer, a condition possibly caused by the toxic locations used in the filming of Stalker.[Unreliable source]
Tarkovsky was the recipient of numerous accolades throughout his career, including the FIPRESCI prize, the Prize of the Ecumenical Jury and the Grand Prix Spécial du Jury at the Cannes Film Festival in addition to the Golden Lion at the Venice Film Festival for his debut film, Ivan's Childhood as well as the BAFTA Film Award for The Sacrifice. In 1990, he was posthumously awarded the Soviet Union's prestigious Lenin Prize. Three of his films—Andrei Rublev, Mirror, and Stalker—featured in Sight & Sound 2012 poll of the 100 greatest films of all time. |
Andrei Tarkovsky | Life and career | Life and career |
Andrei Tarkovsky | Childhood and early life | Childhood and early life
Andrei Tarkovsky was born in the village of Zavrazhye in the Yuryevetsky District of the Ivanovo Industrial Oblast (modern-day Kadyysky District of the Kostroma Oblast, Russia) to the poet and translator Arseny Aleksandrovich Tarkovsky, a native of Yelysavethrad (now Kropyvnytskyi, Ukraine), and Maria Ivanova Vishnyakova, a graduate of the Maxim Gorky Literature Institute who later worked as a proofreader; she was born in Moscow in the Dubasov family estate.
Andrei's paternal grandfather Aleksandr Karlovich Tarkovsky (in ) was a Polish nobleman who worked as a bank clerk. His wife Maria Danilovna Rachkovskaya was a Romanian language teacher who arrived from Iași. interview to the Gordon Boulevard newspaper at the Andrei Tarkovsky media archive, 2007 (in Russian) Andrei's maternal grandmother Vera Nikolayevna Vishnyakova (née Dubasova) belonged to an old Dubasov family of Russian nobility that traces its history back to the 17th century; among her relatives was Admiral Fyodor Dubasov, a fact she had to conceal during the Soviet days. She was married to Ivan Ivanovich Vishnyakov, a native of the Kaluga Governorate who studied law at the Moscow State University and served as a judge in Kozelsk. interview with Tarkovsky's sister Marina Tarkovskaya, Itogy journal, 2 April 2012 (in Russian) from the Brockhaus and Efron Encyclopedic Dictionary, 1890–1907 (Wikisource, in Russian)
According to the family legend, Tarkovsky's ancestors on his father's side were princes from the Shamkhalate of Tarki, Dagestan, although his sister, Marina Tarkovskaya, who conducted detailed research on their genealogy, called it "a myth, even a prank of sorts," stressing that no document confirms this narrative.
Tarkovsky spent his childhood in Yuryevets. His father left the family in 1937, subsequently volunteering for the army in 1941. He returned home in 1943, having been awarded a Red Star after being shot in one of his legs (which he would eventually need to have amputated due to gangrene). Tarkovsky stayed with his mother, moving with her and his sister Marina to Moscow, where she worked as a proofreader at a printing press.
In 1939, Tarkovsky enrolled at the Moscow School No. 554. During the war, the three evacuated to Yuryevets, living with his maternal grandmother. In 1943, the family returned to Moscow. Tarkovsky continued his studies at his old school, where the poet Andrei Voznesensky was one of his classmates. He studied piano at a music school and attended classes at an art school. The family lived on Shchipok Street in the Zamoskvorechye District in Moscow. From November 1947 to spring 1948 he was in the hospital with tuberculosis. Many themes of his childhood—the evacuation, his mother and her two children, the withdrawn father, the time in the hospital—feature prominently in his film Mirror.
In his school years, Tarkovsky was a troublemaker and a poor student. He still managed to graduate, and from 1951 to 1952 studied Arabic at the Oriental Institute in Moscow, a branch of the Academy of Sciences of the Soviet Union. He did not finish his studies and dropped out to work as a prospector for the Academy of Science Institute for Non-Ferrous Metals and Gold. He participated in a year-long research expedition to the river Kureyka near Turukhansk in the Krasnoyarsk Province. During this time in the taiga, Tarkovsky decided to study film. |
Andrei Tarkovsky | Film school student | Film school student
Upon returning from the research expedition in 1954, Tarkovsky applied at the State Institute of Cinematography (VGIK) and was admitted to the film-directing program. He was in the same class as Irma Raush (Irina) whom he married in April 1957.
The early Khrushchev era offered good opportunities for young film directors. Before 1953, annual film production was low and most films were directed by veteran directors. After 1953, more films were produced, many of them by young directors. The Khrushchev Thaw relaxed Soviet social restrictions a bit and permitted a limited influx of European and North American literature, films and music. This allowed Tarkovsky to see films of the Italian neorealists, French New Wave, and of directors such as Kurosawa, Buñuel, Bergman, Bresson, Wajda (whose film Ashes and Diamonds influenced Tarkovsky) and Mizoguchi.
Tarkovsky's teacher and mentor was Mikhail Romm, who taught many film students who would later become influential film directors. In 1956, Tarkovsky directed his first student short film, The Killers, from a short story of Ernest Hemingway. The longer television film There Will Be No Leave Today followed in 1959. Both films were a collaboration between the VGIK students. Classmate Aleksandr Gordon, who married Tarkovsky's sister, in particular directed, wrote, edited, and acted in the two films with Tarkovsky.
During his third year at the VGIK, Tarkovsky met Andrei Konchalovsky. They found much in common as they liked the same film directors and shared ideas on cinema and films. In 1959, they wrote the script Antarctica – Distant Country, which was later published in the Moskovsky Komsomolets. Tarkovsky submitted the script to Lenfilm, but it was rejected. They were more successful with the script The Steamroller and the Violin, which they sold to Mosfilm. This became Tarkovsky's graduation project, earning him his diploma in 1960 and winning First Prize at the New York Student Film Festival in 1961. |
Andrei Tarkovsky | Film career in the Soviet Union | Film career in the Soviet Union
Tarkovsky's first feature film was Ivan's Childhood in 1962. He had inherited the film from director Eduard Abalov, who had to abort the project. The film earned Tarkovsky international acclaim and won the Golden Lion award at the Venice Film Festival in the year 1962. In the same year, on 30 September, his first son Arseny (called Senka in Tarkovsky's diaries) Tarkovsky was born.
thumb|upright|left|Monument to Andrei Tarkovsky at entrance of Gerasimov Institute of Cinematography
In 1965, he directed the film Andrei Rublev about the life of Andrei Rublev, the fifteenth-century Russian icon painter. Andrei Rublev was not, except for a single screening in Moscow in 1966, immediately released after completion due to problems with Soviet authorities. Tarkovsky had to cut the film several times, resulting in several different versions of varying lengths. The film was widely released in the Soviet Union in a cut version in 1971. Nevertheless, the film had a budget of more than 1 million rubles – a significant sum for that period. A version of the film was presented at the Cannes Film Festival in 1969 and won the FIPRESCI prize.
He divorced his wife, Irina, in June 1970. In the same year, he married Larisa Kizilova (née Egorkina), who had been a production assistant for the film Andrei Rublev (they had been living together since 1965). Their son, Andrei Andreyevich Tarkovsky, (nicknamed Andriosha, meaning "little Andre" or "Andre Junior") was born in the same year on 7 August.
In 1972, he completed Solaris, an adaptation of the novel Solaris by Stanisław Lem. He had worked on this together with screenwriter Friedrich Gorenstein as early as 1968. The film was presented at the Cannes Film Festival, won the Grand Prix Spécial du Jury, and was nominated for the Palme d'Or.
From 1973 to 1974, he shot the film Mirror, a highly autobiographical and unconventionally structured film drawing on his childhood and incorporating some of his father's poems. In this film Tarkovsky portrayed the plight of childhood affected by war. Tarkovsky had worked on the screenplay for this film since 1967, under the consecutive titles Confession, White day and A white, white day. From the beginning the film was not well received by Soviet authorities due to its content and its perceived elitist nature. Soviet authorities placed the film in the "third category", a severely limited distribution, and only allowed it to be shown in third-class cinemas and workers' clubs. Few prints were made and the film-makers received no returns. Third category films also placed the film-makers in danger of being accused of wasting public funds, which could have serious effects on their future productivity.Marshall, Herbert. Sight and Sound. Vol 45, no 2. Spring 1976. p. 93. These difficulties are presumed to have made Tarkovsky play with the idea of going abroad and producing a film outside the Soviet film industry.
During 1975, Tarkovsky also worked on the screenplay Hoffmanniana, about the German writer and poet E. T. A. Hoffmann. In December 1976, he directed Hamlet, his only stage play, at the Lenkom Theatre in Moscow. The main role was played by Anatoly Solonitsyn, who also acted in several of Tarkovsky's films. At the end of 1978, he also wrote the screenplay Sardor together with the writer Aleksandr Misharin.
The last film Tarkovsky completed in the Soviet Union was Stalker, inspired by the novel Roadside Picnic by the brothers Arkady and Boris Strugatsky. Tarkovsky had met the brothers first in 1971 and was in contact with them until his death in 1986. Initially he wanted to shoot a film based on their novel Dead Mountaineer's Hotel and he developed a raw script. Influenced by a discussion with Arkady Strugatsky he changed his plan and began to work on the script based on Roadside Picnic. Work on this film began in 1976. The production was mired in troubles; improper development of the negatives had ruined all the exterior shots. Tarkovsky's relationship with cinematographer Georgy Rerberg deteriorated to the point where he hired Alexander Knyazhinsky as a new first cinematographer. Furthermore, Tarkovsky had a heart attack in April 1978, resulting in further delay. The film was completed in 1979 and won the Prize of the Ecumenical Jury at the Cannes Film Festival. In a question and answer session at the Edinburgh Filmhouse on 11 February 1981, Tarkovsky trenchantly rejected suggestions that the film was either impenetrably mysterious or a political allegory.Stalker: Andrei Tarkovsky Talking, in Bold, Christine (ed.), Cencrastus No. 5, Summer 1981, pp. 12 & 13 |
Andrei Tarkovsky | Film career outside the Soviet Union | Film career outside the Soviet Union
During the summer of 1979, Tarkovsky traveled to Italy, where he shot the documentary Voyage in Time together with his long-time friend Tonino Guerra. Tarkovsky returned to Italy in 1980 for an extended trip, during which he and Guerra completed the script for the film Nostalghia. During this period, he took Polaroid photographs depicting his personal life.
Tarkovsky returned to Italy in 1982 to start shooting Nostalghia, but Mosfilm then withdrew from the project, so he sought and received financial backing from the Italian RAI. Tarkovsky completed the film in 1983, and it was presented at the Cannes Film Festival where it won the FIPRESCI prize and the Prize of the Ecumenical Jury. Tarkovsky also shared a special prize called Grand Prix du cinéma de création with Robert Bresson. Soviet authorities lobbied to prevent the film from winning the Palme d'Or, a fact that hardened Tarkovsky's resolve to never work in the Soviet Union again. After Cannes he went to London to stage and choreograph the opera Boris Godunov at the Royal Opera House under the musical direction of Claudio Abbado.
thumb|right|Mug shot of Andrei Tarkovsky at the Latina Refugee Camp of Latina (Italy) in 1985
At a press conference in Milan on 10 July 1984, he announced that he would never return to the Soviet Union and would remain in Western Europe. He stated, "I am not a Soviet dissident, I have no conflict with the Soviet Government," but if he returned home, he added, "I would be unemployed." At that time, his son Andriosha was still in the Soviet Union and not allowed to leave the country. On 28 August 1985, Tarkovsky was processed as a Soviet Defector at a refugee camp in Latina, Italy, registered with the serial number 13225/379, and officially welcomed to the West.
Tarkovsky spent most of 1984 preparing the film The Sacrifice. It was finally shot in 1985 in Sweden, with many of the crew being alumni from Ingmar Bergman's films, including cinematographer Sven Nykvist. Tarkovsky's vision of his film was greatly influenced by Bergman's style.
While The Sacrifice is about an apocalypse and impending death, faith, and possible redemption, in the making-of documentary Directed by Andrei Tarkovsky, in a particularly poignant scene, writer/director Michal Leszczylowski follows Tarkovsky on a walk as he expresses his sentiments on death—he claims himself to be immortal and has no fear of dying. Ironically, at the end of the year Tarkovsky was diagnosed with terminal lung cancer. In January 1986, he began treatment in Paris and was joined there by his son, Andre Jr, who was finally allowed to leave the Soviet Union. What would be Tarkovsky's final film was dedicated to him.
The Sacrifice was presented at the Cannes Film Festival and received the Grand Prix Spécial du Jury, the FIPRESCI prize and the Prize of the Ecumenical Jury. As Tarkovsky was unable to attend due to his illness, the prizes were collected by his son. |
Andrei Tarkovsky | Death | Death
thumb|Andrei and Larisa Tarkovsky's grave, Sainte-Geneviève-des-Bois Russian Cemetery in France
In Tarkovsky's last diary entry (15 December 1986), he wrote: "But now I have no strength left—that is the problem". The diaries are sometimes also known as Martyrology and were published posthumously in 1989 and in English in 1991.
Tarkovsky died in Paris on 29 December 1986. His funeral ceremony was held at the Alexander Nevsky Cathedral. He was buried on 3 January 1987 in the Russian Cemetery in Sainte-Geneviève-des-Bois in France. The inscription on his gravestone, which was erected in 1994, was conceived by Tarkovsky's wife, Larisa, reads: To the man who saw the Angel. Larisa died in 1998 and is buried beside her husband.
Tarkovsky, his wife Larisa, and actor Anatoly Solonitsyn all died from the same type of cancer. Vladimir Sharun, a sound designer for Stalker, was convinced that all three died due to exposure to chemicals released from a chemical plant upstream from where the film was shot. |
Andrei Tarkovsky | Influences and thoughts on film | Influences and thoughts on film
Tarkovsky became a film director during the mid and late 1950s, a period referred to as the Khrushchev Thaw, during which Soviet society opened to foreign films, literature and music, among other things. This allowed Tarkovsky to see films of European, American and Japanese directors, an experience that influenced his own film making. His teacher and mentor at the film school, Mikhail Romm, allowed his students considerable freedom and emphasized the independence of the film director.
Tarkovsky was, according to fellow student Shavkat Abdusalmov, fascinated by Japanese films. He was amazed by how every character on the screen is exceptional and how everyday events such as a Samurai cutting bread with his sword are elevated to something special and put into the limelight. Tarkovsky has also expressed interest in the art of Haiku and its ability to create "images in such a way that they mean nothing beyond themselves".Tarkovsky, Andrei. Sculpting in Time. Trans. Kitty Hunter-Blair. Austin, Texas: University of Texas Press, 2003.
Tarkovsky was also a deeply religious Orthodox Christian, who believed great art should have a higher spiritual purpose. He was a perfectionist not given to humor or humility: his signature style was ponderous and literary, having many characters that pondered over religious themes and issues regarding faith.
Tarkovsky perceived that the art of cinema has only been truly mastered by very few filmmakers, stating in a 1970 interview with Naum Abramov that "they can be counted on the fingers of one hand". In 1972, Tarkovsky told film historian Leonid Kozlov his ten favorite films. The list is as follows: Diary of a Country Priest and Mouchette by Robert Bresson; Winter Light, Wild Strawberries, and Persona by Ingmar Bergman; Nazarín by Luis Buñuel; City Lights by Charlie Chaplin; Ugetsu by Kenji Mizoguchi; Seven Samurai by Akira Kurosawa, and Woman in the Dunes by Hiroshi Teshigahara. He also liked Pier Paolo Pasolini's film The Gospel According to St. Matthew. Among his favorite directors were Buñuel, Mizoguchi, Bergman, Bresson, Kurosawa, Michelangelo Antonioni, Jean Vigo, and Carl Theodor Dreyer.
With the exception of City Lights, the list does not contain any films of the early silent era. The reason is that Tarkovsky saw film as an art as only a relatively recent phenomenon, with the early film-making forming only a prelude. The list has also no films or directors from Tarkovsky's native Soviet Union, although he rated Soviet directors such as Boris Barnet, Sergei Parajanov and Alexander Dovzhenko highly. He said of Dovzhenko's Earth: "I have lived a lot among very simple farmers and met extraordinary people. They spread calmness, had such tact, they conveyed a feeling of dignity and displayed wisdom that I have seldom come across on such a scale. Dovzhenko had obviously understood wherein the sense of life resides. [...] This trespassing of the border between nature and mankind is an ideal place for the existence of man. Dovzhenko understood this."
He was also not a fan of blockbusters or science fiction, largely dismissing the latter for its "comic book" trappings and vulgar commercialism. He equally liked George Lucas's Star Wars according to his son, Andrei A. Tarkovsky. |
Andrei Tarkovsky | Cinematic style | Cinematic style
In a 1962 interview, Tarkovsky argued: "All art, of course, is intellectual, but for me, all the arts, and cinema even more so, must above all be emotional and act upon the heart." His films are characterized by metaphysical themes, extremely long takes, and images often considered by critics to be of exceptional beauty. Recurring motifs are dreams, memory, childhood, running water accompanied by fire, rain indoors, reflections, levitation, and characters re-appearing in the foreground of long panning movements of the camera. He once said: "Juxtaposing a person with an environment that is boundless, collating him with a countless number of people passing by close to him and far away, relating a person to the whole world, that is the meaning of cinema."
Tarkovsky incorporated levitation scenes into several of his films, most notably Solaris. To him these scenes possess great power and are used for their photogenic value and magical inexplicability. Water, clouds, and reflections were used by him for their surreal beauty and photogenic value, as well as their symbolism, such as waves or the forms of brooks or running water. Bells and candles are also frequent symbols. These are symbols of film, sight and sound, and Tarkovsky's film frequently has themes of self-reflection..
Tarkovsky developed a theory of cinema that he called "sculpting in time". By this he meant that the unique characteristic of cinema as a medium was to take our experience of time and alter it. Unedited movie footage transcribes time in real time. By using long takes and few cuts in his films, he aimed to give the viewers a sense of time passing, time lost, and the relationship of one moment in time to another.
Up to, and including, his film Mirror, Tarkovsky focused his cinematic works on exploring this theory. After Mirror, he announced that he would focus his work on exploring the dramatic unities proposed by Aristotle: a concentrated action, happening in one place, within the span of a single day.
Several of Tarkovsky's films have color or black-and-white sequences. This first occurs in the otherwise monochrome Andrei Rublev, which features a color epilogue of Rublev's authentic religious icon paintings. All of his films afterwards contain monochrome, and in Stalker's case sepia sequences, while otherwise being in color. In 1966, in an interview conducted shortly after finishing Andrei Rublev, Tarkovsky dismissed color film as a "commercial gimmick" and cast doubt on the idea that contemporary films meaningfully use color. He claimed that in everyday life one does not consciously notice colors most of the time, and that color should therefore be used in film mainly to emphasize certain moments, but not all the time, as this distracts the viewer. To him, films in color were like moving paintings or photographs, which are too beautiful to be a realistic depiction of life.
Director Ingmar Bergman commented on Tarkovsky:
Contrarily, however, Bergman conceded the truth in the claim made by a critic who wrote that "with Autumn Sonata Bergman does Bergman", adding: "Tarkovsky began to make Tarkovsky films, and that Fellini began to make Fellini films [...] Buñuel nearly always made Buñuel films." This pastiche of one's own work has been derogatorily termed as "self-karaoke". |
Andrei Tarkovsky | Vadim Yusov | Vadim Yusov
Tarkovsky worked in close collaboration with cinematographer Vadim Yusov from 1958 to 1972, and much of the visual style of Tarkovsky's films can be attributed to this collaboration., Museum of Learning. Tarkovsky would spend two days preparing for Yusov to film a single long take, and due to the preparation, usually only a single take was needed.The films of Andrei Tarkovsky: a visual fugue By Vida T. Johnson, Graham Petrie, p. 79. |
Andrei Tarkovsky | Sven Nykvist | Sven Nykvist
In his last film, The Sacrifice, Tarkovsky worked with cinematographer Sven Nykvist, who had worked on many films with director Ingmar Bergman. (Nykvist was not alone: several people involved in the production had previously collaborated with Bergman, notably lead actor Erland Josephson, who had also acted for Tarkovsky in Nostalghia.) Nykvist complained that Tarkovsky would frequently look through the camera and even direct actors through it, but ultimately stated that choosing to work with Tarkovsky was one of the best choices he had ever made. |
Andrei Tarkovsky | Filmography | Filmography
Tarkovsky is mainly known as a film director. During his career he directed seven feature films, as well as three shorts from his time at VGIK. His features are:
Ivan's Childhood (1962)
Andrei Rublev (1966)
Solaris (1972)
Mirror (1975)
Stalker (1979)
Nostalghia (1983)
The Sacrifice (1986)
He also wrote several screenplays. Furthermore, he directed the play Hamlet for the stage in Moscow, directed the opera Boris Godunov in London, and he directed a radio production of the short story Turnabout by William Faulkner. He also wrote Sculpting in Time, a book on film theory.
Tarkovsky's first feature film was Ivan's Childhood in 1962. He then directed Andrei Rublev in 1966, Solaris in 1972, Mirror in 1975 and Stalker in 1979. The documentary Voyage in Time was produced in Italy in 1982, as was Nostalghia in 1983. His last film The Sacrifice was produced in Sweden in 1986. Tarkovsky was personally involved in writing the screenplays for all his films, sometimes with a cowriter. Tarkovsky once said that a director who realizes somebody else's screenplay without being involved in it becomes a mere illustrator, resulting in dead and monotonous films. |
Andrei Tarkovsky | Publications | Publications
Sculpting in Time. University of Texas Press, 1986. .
Time Within Time: The Diaries 1970–1986. Seagull, 1989. . Translated by Kitty Hunter-Blair.
Collected Screenplays. London: Faber & Faber, 2003. .
Instant Light, Tarkovsky Polaroids. London: Thames and Hudson, 2006. . A book of 60 photographs taken by Tarkovsky in Russia and Italy between 1979 and 1984. Edited by Italian photographer Giovanni Chiaramonte and Tarkovsky's son Andrey A. Tarkovsky.
Bright, bright day. Tarkovsky Foundation and White Space Gallery, 2008. A book of Polaroids edited by Stephen Gill. . Edition of 3000 copies.
Tarkovsky: Films, Stills, Polaroids & Writings. London: Thames and Hudson, 2019. . |
Andrei Tarkovsky | Unproduced screenplays | Unproduced screenplays |
Andrei Tarkovsky | ''Concentrate'' | Concentrate
Concentrate (, Kontsentrat) is a never-filmed 1958 screenplay by Tarkovsky. The screenplay is based on Tarkovsky's year in the taiga as a member of a research expedition, prior to his enrollment in film school. It's about the leader of a geological expedition, who waits for the boat that brings back the concentrates collected by the expedition. The expedition is surrounded by mystery, and its purpose is a state secret.
Although some authors claim that the screenplay was filmed, according to Marina Tarkovskaya, Tarkovsky's sister (and wife of Aleksandr Gordon, a fellow student of Tarkovsky during his film school years) the screenplay was never filmed. Tarkovsky wrote the screenplay during his entrance examination at the State Institute of Cinematography (VGIK) in a single sitting. He earned the highest possible grade, "excellent" () for this work. In 1994, fragments of Concentrate were filmed and used in the documentary Andrei Tarkovsky's Taiga Summer by Marina Tarkovskaya and Aleksandr Gordon. |
Andrei Tarkovsky | ''Hoffmanniana'' | Hoffmanniana
Hoffmanniana () is a never-filmed 1974 screenplay by Tarkovsky. The screenplay is based on the life and work of German author E. T. A. Hoffmann. In 1974, an acquaintance from Tallinnfilm approached Tarkovsky to write a screenplay on a German theme. Tarkovsky considered Thomas Mann and E. T. A. Hoffmann, and also thought about Ibsen's Peer Gynt. In the end Tarkovsky signed a contract for a script based on the life and work of Hoffmann. He planned to write the script during the summer of 1974 at his dacha. Writing was not without difficulty, less than a month before the deadline he had not written a single page. He finally finished the project in late 1974 and submitted the final script to Tallinnfilm in October.
Although the script was well received by the officials at Tallinnfilm, it was the consensus that no one but Tarkovsky would be able to direct it. The script was sent to Goskino in February 1976, and although approval was granted for proceeding with making the film, the screenplay was never realized. In 1984, during the time of his exile in the West, Tarkovsky revisited the screenplay and made a few changes. He also considered to finally direct a film based on the screenplay but ultimately dropped this idea. |
Andrei Tarkovsky | Films about Tarkovsky | Films about Tarkovsky
Voyage in Time (1983): documents the travels in Italy of Andrei Tarkovsky in preparation for the making of his film Nostalghia, co-directed with Tonino Guerra.
Tarkovsky: A Poet in the Cinema (1984): directed by Donatella Baglivo.
Moscow Elegy (1987), a documentary/homage to Tarkovsky by Aleksandr Sokurov.
Auf der Suche nach der verlorenen Zeit (1988): Andrej Tarkowskijs Exil und Tod. Documentary directed by Ebbo Demant. Germany.
One Day in the Life of Andrei Arsenevich (1999): French documentary film directed by Chris Marker.
Andrey (2006): a film by Nariné Mktchyan and Arsen Azatyan about Tarkovsky visiting Armenia.
Tarkovsky: Time Within Time (2015): documentary by P. J. Letofsky.
Andrei Tarkovsky: A Cinema Prayer (2019): a poetic documentary by Tarkovsky's son Andrei A. Tarkovsky. |
Andrei Tarkovsky | Awards and commemoration | Awards and commemoration
Numerous awards were bestowed on Tarkovsky throughout his lifetime.
At the Venice Film Festival, the Golden Lion of the for Ivan's Childhood
thumb|Russian stamp, 2007At the Cannes Film Festival, the FIPRESCI prize three times, the Prize of the Ecumenical Jury three times (more than any other director), the Grand Prix Spécial du Jury twice, and the Best Director award once. He was also nominated for the Palme d'Or three times.
In 1987, the BAFTA Award for Best Foreign Language Film of the British Academy of Film and Television Arts for The Sacrifice.
Under the influence of Glasnost and Perestroika, Tarkovsky was finally recognized in the Soviet Union in the Autumn of 1986, shortly before his death, by a retrospective of his films in Moscow. After his death, an entire issue of the film magazine Iskusstvo Kino was devoted to Tarkovsky. In their obituaries, the film committee of the Council of Ministers of the Soviet Union and the Union of Soviet Film Makers expressed their sorrow that Tarkovsky had to spend the last years of his life in exile.
Posthumously, he was awarded the Lenin Prize in 1990, one of the highest state honors in the Soviet Union. In 1989, the Andrei Tarkovsky Memorial Prize was established, with its first recipient being the Russian animator Yuri Norstein. In three consecutive events, the Moscow International Film Festival awarded the Andrei Tarkovsky Award in 1993, 1995, and 1997.
In 1996, the Andrei Tarkovsky Museum opened in Yuryevets, his childhood town. A minor planet, 3345 Tarkovskij, discovered by Soviet astronomer Lyudmila Karachkina in 1982, has been named after him.
Tarkovsky has been the subject of several documentaries. Most notable is the 1988 documentary Moscow Elegy, by Russian film director Alexander Sokurov. Sokurov's own work has been heavily influenced by Tarkovsky. The film consists mostly of narration over stock footage from Tarkovsky's films. Directed by Andrei Tarkovsky is a 1988 documentary film by Michal Leszczylowski, an editor of the film The Sacrifice. Film director Chris Marker produced the television documentary One Day in the Life of Andrei Arsenevich as an homage to Andrei Tarkovsky in 2000.
At the entrance to the Gerasimov Institute of Cinematography in Moscow, there is a monument that includes statues of Tarkovsky, Gennady Shpalikov and Vasily Shukshin. |
Andrei Tarkovsky | Reception and legacy | Reception and legacy
Andrei Tarkovsky and his works have received praise from many filmmakers, critics and thinkers.
The Swedish filmmaker Ingmar Bergman was quoted as saying: "Tarkovsky for me is the greatest [of us all], the one who invented a new language, true to the nature of film, as it captures life as a reflection, life as a dream".Title quote of 2003 Tarkovsky Festival Program, Pacific Film Archive
The Japanese filmmaker Akira Kurosawa remarked on Tarkovsky's films as saying: "His unusual sensitivity is both overwhelming and astounding. It almost reaches a pathological intensity. Probably there is no equal among film directors alive now." Kurosawa also commented: "I love all of Tarkovsky's films. I love his personality and all his works. Every cut from his films is a marvelous image in itself. But the finished image is nothing more than the imperfect accomplishment of his idea. His ideas are only realized in part. And he had to make do with it."
The Iranian filmmaker Abbas Kiarostami remarked that: "Tarkovsky's works separate me completely from physical life, and are the most spiritual films I have seen".
The Polish filmmaker Krzysztof Kieślowski commented that: "Andrei Tarkovsky was one of the greatest directors of recent years," and regarded Tarkovsky's film Ivan's Childhood as an influence on his own work.
The Turkish filmmaker Nuri Bilge Ceylan said that when he first discovered the films of Andrei Tarkovsky as a college student, unsure of what he wanted to do with his life, he was utterly baffled by the lauded Soviet master. He walked out of a screening of Solaris at the halfway point, and stopped a VHS tape of Mirror at a similar juncture. Today, he considers the latter to be the greatest film ever made. "I've seen it maybe 20 times," he says.
The Armenian filmmaker Sergei Parajanov remarked that watching Tarkovsky's film, Ivan's Childhood was his main inspiration to become a filmmaker by saying: "I did not know how to do anything and I would not have done anything if there had not been Ivan's Childhood".
The Austrian filmmaker Michael Haneke voted for Mirror on his top 10 films in the 2002 Sight & Sound directors' poll and later said that he has seen the picture at least 25 times.
The American filmmaker Stan Brakhage said that: "I personally think that the three greatest tasks for film in the 20th century are (1) To make the epic, that is to tell the tales of the tribes of the world. (2) To keep it personal, because only in the eccentricities of our personal lives do we have any chances at the truth. (3) To do the dream work, that is, to illuminate the borders of the unconscious. The only filmmaker I know that does all these three things equally in every film he makes is Andrei Tarkovsky, and that's why I think he's the greatest living narrative filmmaker."
The German filmmaker Wim Wenders dedicated his film Wings of Desire to Tarkovsky (along with François Truffaut and Yasujirō Ozu).
The French filmmaker Chris Marker directed a documentary film as a homage to Tarkovsky called One Day in the Life of Andrei Arsenevich and used Tarkovsky's concept of "The Zone" (from the film, Stalker) for his 1983 film essay, Sans Soleil.
The Greek filmmaker Theo Angelopoulos regarded Tarkovsky's film Stalker as one of the films that influenced him.
The Polish filmmaker Andrzej Żuławski remarked that: "If anybody influenced anybody, it's me being influenced by Tarkovsky, not the reverse", and called Tarkovsky's film Andrei Rublev a "masterpiece".
The Greek-Australian filmmaker Alex Proyas was "extremely influenced" by Tarkovsky's work and cited Stalker as one of his favorite films.
The French philosopher Jean-Paul Sartre highly praised Tarkovsky's film Ivan's Childhood, saying that it was one of the most beautiful films he had ever seen.
The Japanese anime filmmaker Mamoru Oshii, known for his works such as Ghost in the Shell, was influenced by Tarkovsky.
The Indian-born British American novelist Salman Rushdie praised Tarkovsky and his work Solaris by calling it "a sci-fi masterpiece".Rushdie, Salman. Step Across This Line: Collected Nonfiction 1992–2002. New York: Random House, 2002, p. 335.
Film historian Steven Dillon says that much of subsequent film was deeply influenced by the films of Tarkovsky.
Mexican filmmaker Alejandro González Iñarritu is a huge fan of Tarkovsky. He once said in an interview: "Andrei Rublev is maybe my favorite film ever", and in another interview, he added: "I remember, the first time I saw a Tarkovsky film, I was shocked by it. I did not know what to do. I was shocked by it. I was fascinated, because suddenly I realized that film could have so many more layers to it than what I had imagined before". There are many direct references and hidden tributes to Tarkovsky's movies in Iñarritu's 2015 Oscar-winning drama The Revenant.
Danish film director Lars von Trier is a fervent admirer of Tarkovsky. He dedicated his 2009 film Antichrist to him, and, while discussing it with critic David Jenkins, asked: "Have you seen Mirror? I was hypnotised! I've seen it 20 times. It's the closest thing I've got to a religion – to me he is a god".
The Japanese composer Ryuichi Sakamoto was an admirer of Tarkovsky's work, describing his penultimate solo album, async as "a soundtrack for an imaginary Tarkovsky film." On Tarkovsky's overall influence on his own work, Sakamoto stated, "As I've been making music and trying to go deeper and deeper, I was finally able to understand what the Tarkovsky movies are about — how symphonic they are — it's almost music. Not just the sounds — it's a symphony of moving images and sounds. They are more complex than music." |
Andrei Tarkovsky | Film festival | Film festival
Two film festivals have been named in his honor:
International Human Rights Film Festival "Stalker", named after the film held annually in Moscow and regional centres since 1995
International Film Festival "Zerkalo" named after Andrei Tarkovsky (meaning "mirror"), "for fans of intellectual cinema"; also known as Tarkovsky Film festival – Zerkalo, Zerkalo International Film Festival, Andrei Tarkovsky Zerkalo International Film Festival, 4 July 2020. or simply Zerkalo, The festival is organized by a committee headed by Mikhail Men, governor of Ivanovo Oblast. Sister of Andrei Tarkovsky, Marina Tarkovsky was one of the co-founders and organizers. From 2010 the festival was directed by Pavel Lungin. In 2020, the president of the festival was Russian director Sergei Bodrov. Owing to the COVID-19 pandemic in Russia, the 14th edition was held online in 2020, and appears to be the last one held, . The festival awards a number of prizes, including the Special Award for Contribution to Andrei Tarkovsky's Cinema. (English version) Held in Ivanovo since 2007, the festival is held in July each year, with the 16th edition scheduled for 22–27 July, to be held in various cities in the Ivanovo region, with special screenings in Moscow. Films from France, India, Greece, Serbia, Colombia, Kazakhstan and other countries were entered into the competition, and a gala night was dedicated to Tarkovsky's 90th birthday, on the main square of his hometown of Yuryevets on 22 July. |
Andrei Tarkovsky | See also | See also
European art cinema
Slow cinema
Moscow International Film Festival |
Andrei Tarkovsky | References | References |
Andrei Tarkovsky | Bibliography | Bibliography
Schmidt, Stefan W. (2016). "Somatography and Film: Nostalgia as Haunting Memory Shown in Tarkovsky's Nostalghia." Journal of Aesthetics and Phenomenology, 3 (1): 27–41. Somatography and Film: Nostalgia as Haunting Memory Shown in Tarkovsky's Nostalghia
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Andrei Tarkovsky | Notes | Notes |
Andrei Tarkovsky | Further reading | Further reading
|
Andrei Tarkovsky | External links | External links
Andrei Tarkovsky at Senses of Cinema
Website about Andrei Tarkovsky, Films, Articles, Interviews
Andrei Tarkovsky: Biography wrestles with the filmmaker's remarkable life
Nostalghia.com - An Andrei Tarkovsky Information Site, at Film Studies Program in the Department of Communication and Culture, University of Calgary
A.Tarkovsky's Days in Armenia
Category:1932 births
Category:1986 deaths
Category:Academic staff of High Courses for Scriptwriters and Film Directors
Category:Burials at Sainte-Geneviève-des-Bois Russian Cemetery
Category:Cannes Film Festival Award for Best Director winners
Category:Deaths from lung cancer in France
Category:Directors of Golden Lion winners
Category:Filmmakers who won the Best Foreign Language Film BAFTA Award
Category:Gerasimov Institute of Cinematography alumni
Category:Pacifists
Category:People from Kostroma Oblast
Category:People's Artists of the RSFSR
Category:Recipients of the Lenin Prize
Category:Russian Soviet Federative Socialist Republic people
Category:Russian science fiction film directors
Category:Soviet diarists
Category:Soviet documentary film directors
Category:Soviet emigrants to France
Category:Soviet emigrants to Italy
Category:Soviet film directors
Category:Soviet male screenwriters
Category:Soviet non-fiction writers
Category:Soviet opera directors
Category:Soviet people of Polish descent
Category:Soviet people of Romanian descent
Category:Soviet screenwriters
Category:Writers from Kostroma Oblast |
Andrei Tarkovsky | Table of Content | Short description, Life and career, Childhood and early life, Film school student, Film career in the Soviet Union, Film career outside the Soviet Union, Death, Influences and thoughts on film, Cinematic style, Vadim Yusov, Sven Nykvist, Filmography, Publications, Unproduced screenplays, ''Concentrate'', ''Hoffmanniana'', Films about Tarkovsky, Awards and commemoration, Reception and legacy, Film festival, See also, References, Bibliography, Notes, Further reading, External links |
Ambiguity | Short description | thumb|250px|alt=Drawing of the back an anthropomorphic caterpillar, seated on a toadstool amid grass and flowers, blowing smoke from a hookah; a blonde girl in an old-fashioned frock is standing on tiptoe to peer at the caterpillar over the toadstool's edge|Sir John Tenniel's illustration of the Caterpillar for Lewis Carroll's Alice's Adventures in Wonderland is noted for its ambiguous central figure, whose head can be viewed as either a man's face with a pointed nose and chin smoking a pipe, or as the end of an actual caterpillar, with the first two right "true" legs visible (1865)."And do you see its long nose and chin? At least, they look exactly like a nose and chin, that is don't they? But they really are two of its legs. You know a Caterpillar has got quantities of legs: you can see more of them, further down." Carroll, Lewis. The Nursery "Alice". Dover Publications (1966), p 27.
Ambiguity is the type of meaning in which a phrase, statement, or resolution is not explicitly defined, making for several interpretations; others describe it as a concept or statement that has no real reference. A common aspect of ambiguity is uncertainty. It is thus an attribute of any idea or statement whose intended meaning cannot be definitively resolved, according to a rule or process with a finite number of steps. (The prefix ambi- reflects the idea of "two", as in "two meanings").
The concept of ambiguity is generally contrasted with vagueness. In ambiguity, specific and distinct interpretations are permitted (although some may not be immediately obvious), whereas with vague information it is difficult to form any interpretation at the desired level of specificity. |
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