Born July 20, 1839, in Demmin, Pomerania; died Aug. 15, 1884, in Leipzig. German pathologist.

Cohnheim studied medicine at the universities of Würzburg, Marburg, Greifswald, and Berlin. In 1864 he was an assistant to R. Virchow. Cohnheim was professor of pathological anatomy at Kiel from 1868, Breslau (now Wroclaw) from 1872, and Leipzig from 1878 to 1884. His principal work was a manual in general pathology, in which he set forth a theory of the origin of tumors (”Cohnheim’s embryonic theory”). According to this theory, tumors are formed from embryonic rudiments that remain unutilized during the origin and growth of the embryo; subsequently, when the life processes of surrounding tissues slacken, these cells, in Cohnheim’s opinion, begin to reproduce intensively. He eleborated a vascular theory of inflammation and a theory concerning the terminal arteries (vessels) and the pathogenesis of an infarct. Cohnheim’s works greatly influenced the development of pathology.