Bütschli, Otto(ô`tō büch`lē), 1848–1920, German zoologist. He was professor of zoology at the Univ. of Heidelberg. His researches on invertebrate animals advanced knowledge of the development of gastropods, insects, and other forms; the structure of nematode worms; and processes of division of the nucleus and cell. A significant contribution was his theory (1878) of the structure of protoplasm, which suggested that it is alveolar or foamlike; he helped to establish that it is fluid in nature.
Born May 3, 1848, in Frankfurt am Main; died Feb. 3, 1920, in Heidelberg. German zoologist. Bütschli studied mineralogy, chemistry, and zoology in Karlsruhe, Heidelberg, and Leipzig and from 1878 was a professor at the University of Heidelberg. He worked in the areas of cytology and protistology. He advanced the theory of a cellular or frothy structure of protoplasm and methodically researched the stages of meiotic cell division and the processes of fertilization in animals. He attempted to explain the origin of asymmetry in the structure of gastropod mollusks and five-pointed symmetry in echinoderms. He was the author of the fundamental compendium The Simplest Animals (vol. 1, parts 1-3, 1882-89) and Lectures on Comparative Anatomy (vols. 1-6, 1910-34).