STUDIES ON TRANSPLANTATION IN PLANARIA

Abstract

A new technique of transplantation in Planaria which gives a high percentage of "takes" is described. The head, or part of it, which is the most active region of the body of Planaria, when transplanted into the post-pharyngeal region or relatively less active region of the body, is capable, not only of acting as an organizer and completely reversing the polarity of the region anterior to it, but also of inhibiting the formation of a head at a cut surface several mm. anterior to it. Both homoio-plastic and heteroplastic transplantations were performed in Planaria dorotocephala and P. maculata. The results of heteroplastic transplantations show that the action of the graft is not specific. The fate of the graft does not depend primarily upon the degree of its specialization but on the degree of physiological activity of the level of the body from which it is taken and also on the region of the body of the host in which it is implanted. The fate of the graft also depends upon the size of the graft, degree of "take," and orientation of the graft in the body of the host.