RECONSTITUTIONAL PATTERNS IN EXPERIMENT 



383 



Homoplastic and heteroplastic grafts of ganglionic pieces into the an- 

 terior prepharyngeal region (Santos, Okada, and Sugino) may induce 

 short postcephalic regions, the longest about equal in length to the dis- 

 tance between level of implantation and host head (Fig. 128, A-C). 

 Grafts at the pharyngeal level usually induce a prepharyngeal outgrowth 

 and a pharynx in the host body posterior to the outgrowth (Fig. 128, 



U 



Fig. 128, A-E. — Ganglionic grafts of Dugesia ( = Euplanaria): regeneration of graft and 

 induced reorganization of host. A, homoplastic, D. dorotocephala, in anterior prepharyngeal 

 region, has induced cylindrical outgrowth with dorsal epithelium on outer surface; B, hetero- 

 plastic, D. tigrina novangUae to D. dorotocephala, host decapitated twice; C, heteroplastic, 

 D. tigrina novangliae to pharyngeal region of D. dorotocephala with removal of host pharynx 

 with old pharynx remaining, induces prepharyngeal region and pharynx; E, heteroplastic, 

 D. tigrina novangliae to pharyngeal region of D. dorotocephala with removal of host pharynx 

 and head, induces prepharyngeal region and pharynx posterior to graft, and regenerating host 

 head induces another pharynx anterior to the graft (from Santos, 1929, 193 1). 



D, E). Other examples of induction by heteroplastic grafts in the pharyn- 

 geal region, showing the induced modifications of the alimentary tract, 

 appear in Figure 129 from Miller's experiments. Details are given in the 

 legends. In A, B, and C of Figure 129 a pharynx is induced posterior to 

 the graft, and in B and C regeneration of a host head after later decapita- 

 tion anterior to the graft-level is completely inhibited; the two branches 

 of the alimentary tract at the original anterior end after this decapitation 

 in B indicate its reorganization into a posterior end. In Figure 129, D, 

 the graft has induced a pharynx posteriorly, another anteriorly with re- 



