Microstomum caudatum, after being kept from experiences with hydra for twenty-two asexual generations, will feed upon hydra and appropriate the nematocysts. The removal of all of the ganglia and the intervention of extensive regeneration in M. caudatum, sixteen asexual generations removed from hydra, will not prevent the transmitting of factors for the instinct that deals with the manipulation of the nematocysts of hydra by Microstomum. The appropriated nematocysts have been used by an individual as much as fifteen asexual generations removed from hydra. The instinct is in this case, therefore, not resident in the neuroplasm and the factor determining its presence is transmitted from generation to generation by the soma and not by germplasm.