and it affects the vowel quantity. In Wintu, the vowel ablaut occurs only in the mutations of some verb-root vowels (called dissimilation), or in some root-deriving suffixes (assimilation). Root-vowel dissimilation is conditioned by the height of the vowel in the following syllable, while the suffix vowel assimilation is conditioned by the quantity of the vowel in the preceding syllable. An example of dissimilation takes place when /e/ and /o/, which occurs only in root syllables, are raised in height when they are preceded by a single consonant and followed by the low vowel /a/ in the next syllable. Ex. lEla-/lila/ "to transform" and lElu-/lelu/ "transform". An example of dissimilation takes place when the morphophoneme [V]assimilates completely to the quality of the vowel that precedes in the previous syllable. Ex.cewVlVlVha=/ceweleleha/ "many to be wide open". Consonant ablaut A small amount of consonant ablaut is also present in Wintu, for example before word juncture /cʼ/ and /b/ change in /p/. Nouns Substantives are marked for aspect and case. There are two different types of substantives: those formed directly from roots (pronouns, non possessed nouns, kinship terms) and those based on forms of complex derivation from radical and stems (mostly nouns). Pronouns can be singular, dual, and plural. They have particular suffixes (possessive for instrumental functions and for marking plural humans.) They are also very similar to verbs. Nouns have a variety of roots, they are an open class, they may show number in rare forms and they do not distinguish possessive from instrumental functions. Nouns can be classified in possessed and non possessed. The noun is composed of two elements:a stem and a suffix. The stem is usually a root. The suffixes specify numbers, animateness, personification or individuation. Some nouns have the same stem but have a different generic and particular meaning. Ex. /tu/ (particular aspect) eye; (generic aspect) face(s). The suffixes of the nouns can also have different cases: object [um](sedem-coyote), genitive[un](seden), locative [in], instrumental [r], possessive[t], emphatic possessive (reduplication of the last syllable). Verbs Verbs are the wider class of words in Wintu. Also several nouns derivate from verbs. The category of verbs has a very sophisticated morphological structure. Pitkin (1964) identifies three stem forms: indicative, imperative and nominal. Prefixes: optional in occurrence, when affixed directly to roots are followed by a hyphen juncture. Roots: the most part are monosyllabic and with the shape CVC or CVꞏC. Two important processes