 Driesch concluded with an epigenetic account, but an epigenesis relying strictly on materialistic factors (at least that was his initial response; Driesch did turn later to a version of vitalism). The early embryo retains its totipotency, he concluded. The fertilized egg clearly has the capacity to become a whole organism and so, apparently, do the cells after the early cell divisions. Not a mosaic of cells already predetermined by their inherited determinants in the nucleus, the early embryonic stages are instead a population of separate totipotent organisms, each capable of becoming a whole. It is only the interactions among them under normal conditions that lead to a complex, organized, integrated differentiated organism.