WEISMANN, AUGUST (1834- ), German biologist, was born at Frankfort-on-Main, on the 1yth of January 1834, and studied medicine in Gottingen. After spending three years in Rostock, he visited successively Vienna (1858), Italy (1859) and Paris (1860), and from 1861 to 1862 he acted as private physician to the archduke Stephen of Austria at Schaumburg Palace. In 1863 he went to Giessen to devote himself to biological study under Leuckart, and in 1866 he was appointed extraordinary professor of zoology at Freiburg, becoming ordinary professor a few years later. His earlier work was largely concerned with purely zoological investigations, one of his earliest works dealing with the development of the Diptera. Microscopical work, however, became impossible to him owing to impaired eyesight, and he turned his attention to wider problems of biological inquiry. Between 1868 and 1876 he published a series of papers in which he attacked the question of the variability of organisms; these were published in an English translation by R. Meldola in 1882, under the title Studies in the Theories of Descent, Darwin himself contributing a preface in which the importance of the nature and cause of variability in individuals was emphasized. Weismann's name, however, is best known as the author of the germ-plasm theory of heredity, with its accompanying denial of the transmission of acquired characters a theory which on its publication met with considerable opposition, especially in England, from orthodox Darwinism. A series of essays in which this theory is expressed was collected and published in an English translation (Essays upon Heredity and Kindred Biological Problems, vol. i. 1889, vol. ii. 1892). Weismann published many other works devoted to the exposition of his biological views, among them being Die Dauer des Lebens; Vererbung; Ewigkeit des Lebens; Die Kontinuitat des Keimplasmas als Grundlage einer Theorie der Vererbung; Das Keim- plasma; Die Allmacht der Naturzuchiung; Aussert Einfliisse als Entwicklung'sreize; Neue Gedanken zur Vererbungsfrage, and Germinal-Selektion.
For an account of his doctrines the reader is referred to the articles on HEREDITY, REGENERATION and REPRODUCTION.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)