(b. Schiltern, Austria, 8 February 1845; d. Vienna, Austria, 23 October 1920), pathology.
The son of a barrelmaker, Weichselbaum attended the gymnasium in Krems, Austria, from 1855 to 1863 and studied medicine at the Imperial Medical Surgical Military Hospital in Vienna, receiving the M.D. in 1869. He subsequently served as assistant to Rokitansky’s student Josef Engel in the medical corps and in 1875 became anatomical demonstrator at the First Imperial and Royal Military Hospital in Vienna, in 1877 he received the venia legendi for pathological anatomy at the University of Vienna. In 1882 he was named chief demonstrator at the Rudolf Hospital in Vienna, and in 1885 he became associate professor. From 1893 to 1916 he was director of the Pathological-anatomical Institute of the University of Vienna, and in 1912 he became rector of the university.
Weichselbaum was among the first to recognize the importance of bacteriology for pathological anatomy. This fact is reflected in his discovery of the meningococcus and of the diplococcus lanceolatus pneumoniae, which bears his name, as well as in his studies on miliary tuberculosis. Weichselbaum was also extremely receptive to the newly developing science of serology. It was, in fact, while serving as assistant in Weichselbaum’s laboratory that Karl Landsteiner discovered interagglutination between serum and blood cells.
Moreover, Weichselbaum was one of the first to stress the importance of “constitutional pathology.” In his investigations of the pancreas of patients with diabetes mellitus he very early drew attention to the crucial role of the islets of Langerhans, the organs in which insulin was later discovered.
Weichselbaum’s major publications include Grundriss der pathologischen Histologie (Leipzig-Vienna, 1892), translated by W. R. Dawson as The Elements of Pathological Histology (London, 1895); Parasitologie (Jena, 1898); and Epidemiologie (Jena, 1899).
On his life and work, see the notice by Siegmund Exner, in Almanach der Akademie der Wissenschaften in Wien, 71 (1921), 152–155.