An eminent German biologist, born at Potsdam; carried through his medical studies at Berlin and Vienna; early evinced an enthusiasm for zoology, and, after working for some time at Naples and Messina, in 1865 became professor of Zoology at Jena; here he spent a life of unceasing industry, varied only by expeditions to Arabia, India, Ceylon, and different parts of Europe in the prosecution of his scientific theories; he was the first among German scientists to embrace and apply the evolutionary theories of Darwin, and along these lines he has produced several works of first-rate importance in biology; his great works on calcareous sponges, on jelly-fishes, and corals are enriched by elaborate plates of outstanding value; he made important contributions to the Challenger reports, and was among the first to outline the genealogical tree of animal life; his name is associated with far-reaching speculations on heredity, sexual selection, and various problems of embryology; "The Natural History of Creation," "Treatise on Morphology," "The Evolution of Man," are amongst his more popular works; born 1834.