Hans Adolf Eduard Driesch - Experiments in Embryology

Experiments in Embryology

From 1891 Driesch worked in Naples at the Marine Biological Station, where until 1901 he continued to experiment and seek a theoretical formulation of his results. He enquired into classical and modern philosophy in his search for an adequate theoretical overview and ended by adopting an Aristotlean teleological theory of entelechy.

Under the influence of his teacher Haeckel, Driesch had tested the mechanistic embryological theories of another of Haeckel's students, Wilhelm Roux. By 1895 Driesch's experiments on the sea urchin embryo suggested that it was possible to remove large pieces from eggs, shuffle the blastomeres and interfere in many ways without affecting the resulting embryo. It appeared that any single monad in the original egg cell was capable of forming any part of the completed embryo. This important refutation of both preformation and the mosaic theory of Wilhelm Roux was to be subject to much discussion in the ensuing years, and caused friction among Driesch, Roux and Haeckel.

In his work on sea urchins, dividing cells of the embryo after the first cell-division, he expected each cell to develop into the corresponding half of the animal to which it has been destined or preprogrammed, but instead found that each developed into a complete sea urchin. This also happened at the four-cell stage: entire larvae ensued from each of the four cells, albeit smaller than usual. Driesch's findings brought about the adoption of the terms "totipotent" and "pluripotent" cell, referring respectively to a cell that can generate every cell in an organism and one that can generate nearly every cell. Driesch's results were confirmed with greater precision by Hans Spemann.