Weismann, August (1834-1914), a German biologist, developed the germ-plasm theory of heredity. He is known for his writings on evolution and was a supporter of Charles Robert Darwin's theory of evolution.

August Friedrich Leopold Weisman was born Jan. 17, 1834, in Frankfurt (am Main), Germany. He held a medical degree, and while practicing medicine also studied insect development and metamorphosis. Later in his career, he turned his attention to the germ plasm, his term for the factors of inheritance in the sex cells. He devised an experiment to dispel the notion of the time that characteristics acquired during an individual's lifetime can be passed on to future generations. He cut off the tails of hundreds of mice, noting that all the offspring were born with complete tails. Weismann laid out his argument that hereditary material is resistant to the environment in his 1892 book, The Germ Plasm.

Weismann entered the University of Göttingen in 1852 to study medicine. After receiving his medical degree in 1856, he worked as an assistant at a hospital in Rostock. For the next several years, he held a number of jobs, including that of private physician to the archduke of Austria. In 1863, he decided to pursue his interest in zoology, and began teaching comparative anatomy and zoology at the University of Freiburg. He was appointed full professor in 1874. Before retiring from Frieburg in 1912, he served as director of the university's Zoological Institute.