Driesch's recombination experiment proved:
After initial isolation experiments showing totipotency, Driesch performed recombination tests reassembling separated blastomeres or stacking isolated animal halves together in different orientations. Recombined cells interacted dynamically and compensated to produce normal albeit smaller pluteus larvae, not mosaics of partial parts expected under mosaic theory. He concluded cell fate depends intimately on relative position within whole system rather than prelocalized autonomous determinants, defining harmonious equipotential system where each part potential governed by community. This recombination proved conditional development, where intercellular signaling and position determine destiny. Findings overturned Roux's mosaic model and established embryonic field concept.
Ref: Driesch, 1891-1908 sea urchin recombination; Gilbert Chapter 3: Evidence for conditional development.