1. Homoplastic transplantation in Pelmatohydra oligactis has been studied with implants obtained from different body levels.
2. As a result of the regulation of the host, assimilation of the graft has been recorded in all cases. The frequency of assimilation is higher when graft and host are composed of cells having the same (or nearly the same) developmental potentiality.
3. Pedal disk is usually not assimilated, but maintains its own properties following implantation.
4. No gradient of induction potency can be demonstrated in this animal. Perhaps owing to unknown intrinsic factors, the induction power is limited to the cells of the hypostome.
5. A typical induced hydranth is always composed of hypostome supplied by the graft itself, and of tentacles and body derived from the host.