Cohnheim, Julius Friedrich (1839–1884),
German pathologist. A pupil of Rudolf Virchon at Berlin's Pathological Institute, Cohnheim made pioneering investigations into the causes of inflammation. In 1867 he found that inflammation is the result of the passage of white blood cells into the tissues through capillary walls and that pus consists mainly of disintegrated white blood cells. After witnessing Robert Koch demonstrate that the anthrax bacillus is infectious, Cohnheim himself successfully induced tuberculosis in a rabbit and thus paved the way for Koch's discovery of the tubercle bacillus. Cohnheim also developed the now standard procedure of freezing tissue before cutting it into thin slices for microscopic examination. In 1865 he described the arrangements seen in the transverse sections of muscle fiber; these patterns are now known as Cohnheim's areas.