<Tr> <Th> Known for </Th> <Td> germ plasm theory </Td> </Tr> <Tr> <Th> Awards </Th> <Td> Darwin--Wallace Medal (Silver, 1908) </Td> </Tr> <P> August Friedrich Leopold Weismann (17 January 1834--5 November 1914) was a German evolutionary biologist . Ernst Mayr ranked him as the second most notable evolutionary theorist of the 19th century, after Charles Darwin . Weismann became the Director of the Zoological Institute and the first Professor of Zoology at Freiburg . </P> <P> His main contribution involved germ plasm theory, at one time also known as Weismannism, according to which inheritance (in a multicellular organism) only takes place by means of the germ cells--the gametes such as egg cells and sperm cells . Other cells of the body--somatic cells--do not function as agents of heredity . The effect is one - way: germ cells produce somatic cells and are not affected by anything the somatic cells learn or therefore any ability an individual acquires during its life . Genetic information cannot pass from soma to germ plasm and on to the next generation . Biologists refer to this concept as the Weismann barrier . This idea, if true, rules out the inheritance of acquired characteristics as proposed by Jean - Baptiste Lamarck . </P>

Who refuted the theory of pangenesis with his classic experiment on mice tails