Driesch experiment

Hans Driesch experiment on Sea Urchins (1902)

    Hans Driesch tested Wilhelm Roux's theory of development, with sea urchins instead of frogs. Instead of destroying one blastomere, he agitated sea urchin embryos at the two- & four-cell stage until they disassociated into separate cells. Each cell developed as a complete larval sea urchin, somewhat smaller than normal. This Driesch took as evidence for a totipotent or pluripotent capacity of embryonic cells, meaning that each cell retained the capacity to develop normally. [Contrast 'retained the capacity" with "retained all the information necessary ...."]. In Driesch's interpretation, this implied that development was a consequence of external factors operating on the cells. This conclusion was opposite to that of Roux, who argued that development was the manifestation of internal properties.

    At the latter blastula stage of development, Driesch showed that separation of the upper ('animal') from the lower ('vegetal') halves allowed the 'animal' portion to development substantially to maturity, whereas the 'vegetal' half remained essentially undifferentiated.

Text material © 2021 by Steven M. Carr