August Weissmann was a German biologist who is best known for his contributions to evolutionary theory, specifically for his germ-plasm theory of heredity. Weissmann was born in Frankfurt, Germany. At the age of 18, he began his study of medicine at Göttingen University which he attended until 1856. After completing his education, Weissmann practiced medicine until 1863, at which time he turned his attention to the study of biology and zoology. In 1867, Weissmann became a professor of zoology at the University of Freiburg. He first served at the medical school associated with the university and later at a new Institute of Zoology. Weissmann remained in this capacity until 1912.

During this time Weissmann explored a variety of areas, most notably the embryology of insects and crustaceans. He is especially noted for his evaluations of the two-winged flies, the Diptera. He also conducted studies of Hydrozoa (a class of invertebrates which...