WEISMANN, yis'min, August, German biologist: b. Frankfurt-on-the-Main, 17 Jan. 1834: d. 6 Nov. 1914. After studying medicine In Gottingen University he was clinical assist ant at Rostock in 1856-57 and in the course of the three years 1858-60 visited Vienna, Italy and Paris, devoting himself especially to studies in the natural sciences. He lived for a year at Schaumburg Castle as body physician to the Archduke Stephen of Austria and in 1863 went to Giessen to prosecute his zoological studies under Leuelcart. Having qualified as a lec turer in the University of Freiburg, he was appointed extraordinary professor there in 1866 and ordinary professor in 1873. His first published work was a treatise on the 'Develop ment of the Diptera' (18M). It was followed by a work 'On the Influence of Isolation on the Formation of Species' (1872) and 'Studien zur Descendcnztheorie' (1875-76). This work, translated into English in 1882 by Professor Meldola under the title 'Studies in the Theory of Descent' (with a preface by Charles Dar win), treats of several important phenomena in natural history from the standpoint of a thorough believer in the doctrine of natural selection. His 'Beitnisre stir Naturgeschichte der Daphnoiden' (1876-79) and 'Die Ent stehimg der Sexual:ellen bei den Hydro mecisen' (1883) are valuable contributions to the developmental aspect of zoology. A se
ries of treatises followed in which he developed his characteristic theories, among them being Weber die Vererbung' ('On Heredity'), 'Uber die Dauer des Lehens' ('On the Dura tion of Lifc'), (l'eber Leben and Tod' ( 'On Life and Death'), 'Die Kontinui tat des Keimplasmas als Grtmdlage einer Theorie der Verebung' ((The Continuity of the Germ-Plasm as the Basis of a Theory of Heredity'). 'Die Bedeutung der Sexuel len Fortpflanzung fiir die Sclektionstheorie' ((The Significance of Sexual Reproduction for the Theory of Selection'), 'Lieber den Ruck schritt in der Nan& ('On Retrograde Devel cpment in Nature') and 'Amphimixis.' These have appeared in an English translation under the title 'Essays upon Heredity and Kindred Biological Problems' (Vol. I, 1889; Vol. II, 1892). Wcismann's other works include 'Das Keimplasma) (1892), in English as 'Germ Plasm' (1893) ; 'Die Allmacht der Naturziich tunte ((The Omnipotence of Natural Selec tion,' 1893); 'Aeussere Einfliisse als Entwick elungsreize ('External Influences as Stimuli to Development,' 1894); 'Nene Gedanken zur Vererbungsfrage' ('Fresh Thoughts on the Question of Heredity,' 1895); and 'Lieber Ger minalselektion' ((On Germinal Selection,' 1896). See HEREDITY; WEISMANNISM.