Shaking a concept: Hans Driesch and the varied fates of sea urchin blastomeres

Abstract

Among the early adherents of Entwickelungsmechanik Hans Driesch (1867–1941) was certainly the most colourful personality. Born at Kreuznach, a well-known spa on the Nahe river, as the only child of a wealthy Hamburg merchant, he grew up in the liberal atmosphere of that hanseatic city (Driesch 1951). Gifted with the self-confidence that results from a strong mind backed by seemingly unlimited financial means, and driven by a brillant intellect formally trained at the best institutions within reach, he had by his mid-twenties published nearly two dozen descriptive and experimental papers on animal development, and three small books in the border-fields between theoretical biology and philosophy of science. Many of these have fallen justly (and some unjustly) into oblivion, while two or three proved seminal. These last dealt with the shaking and compressing of cleavage stage sea urchin eggs, and served more than any others to shake confidence in the then widely accepted concept of mosaic development (see the previous essays in this series).