science · 15 September 1924 · 100 years ago
death
Died 15 Sep 1924 at age 74 (born 9 Jun 1850).
German zoologist who was a founder of experimental embryology, by which he studied how organs and tissues are assigned their structural form and functions at the time of fertilization. In the 1880s, he experimented with frog eggs. He thought that mitotic cell division of the fertilized egg is the mechanism by which future parts of a developing organism are determined. He destroyed one of the two initial subdivisions (blastomeres) of a fertilized frog egg, obtaining half an embryo from the remaining blastomere. It seemed to him that determination of future parts and functions had already occurred in the two-cell stage and that each of the two blastomeres had already received the determinants necessary to form half the embryo. His theory was later negated by Hans Driesch.
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