Carl Friedrich Wilhelm Ludwig (; 29 December 1816 – 23 April 1895) was a German physician and physiologist. His work as both a researcher and teacher had a major influence on the understanding, methods and apparatus used in almost all branches of physiology. In 1842, Ludwig became a professor of physiology and in 1846 of comparative anatomy. From professorships in Zurich and Vienna he went in 1865 to the University of Leipzig and developed there the Physiological Institute, designated today after him: Carl Ludwig Institute of Physiology. Ludwig researched several topics such as the physiology of blood pressure, urinary excretion, and anesthesia. He received the Copley Medal in 1884 for his research. In 1869, he was elected a foreign member of the Royal Swedish Academy of Sciences. He is credited for inventing the stromuhr. Since 1932, the Carl Ludwig Honorary Medal is awarded by the German Society for Cardiology to outstanding investigators in the area of cardiovascular research. Life Ludwig was born at Witzenhausen, near Kassel, and studied medicine at Erlangen and Marburg, taking his doctor's degree at Marburg in 1839. He made Marburg his home for the next ten years, studying and teaching anatomy and physiology, first as prosector to FL Fick (1841), then as privat-docent (1842), and finally as extraordinary professor (1846). In 1849 he was chosen professor of anatomy and physiology at Zurich, and 6 years afterwards he went to Vienna as professor in the Josephinum school for military surgeons. In 1865 Ludwig was appointed to the newly created chair of physiology at Leipzig, and continued there until his death on 23 April 1895. Appraisal Ludwig's name is prominent in the history of physiology, and he had a large share in bringing about the change in the method of that science that took place in the middle of the 19th century. With his friends Hermann Ludwig Ferdinand von Helmholtz, Ernst Wilhelm von Brücke, and Emil du Bois-Reymond, whom he met for the first time in Berlin in 1847, he rejected the assumption that the phenomena of living animals depend on special biological laws and vital forces different from those that operate in the domain of inorganic nature; and he sought to explain them by reference to the same laws as are applicable in the case of physical and chemical phenomena. This point of view was expressed in Ludwig's celebrated Text-book of Human Physiology (1852–1856), but it is