142 THE BIOLOGY OF STENTOR 



if a large and a very small non-differentiating stentor are grafted 

 together and the mouthparts then excised from the minor compo- 

 nent, simultaneous regeneration and reorganization then occur in 

 the graft complex (Tartar, 1954). For now the reorganization 

 primordium is not to be regarded as induced by the regenerator ; 

 instead the stimulus to regeneration somehow passes from the 

 small cell to the larger, causing it to produce its own state of 

 activation. 



Moreover, in some cases, stage-i regenerators did induce 

 reorganization in non-differentiating partners which were much 

 larger than they. Here it is possible that something of the powerful 

 original stimulus to regeneration, whatever its nature may be, 

 lingers in the early regenerator to boost its inductive influence. 



The relevance of the intimacy of union on the timing and final 

 result of the interaction between a differentiating and a non- 

 differentiating stentor will be important in analyzing the basis of 

 the mutual influences (Weisz, 1956). When the two partners are 

 firmly but not broadly joined, the reorganization primordium 

 induced by a regenerator is noticeably tardy in appearing (Fig. 36A) ; 

 when the joining is tenuous, there is no induction at all (b). 



B 



Fig. 36. Barriers to induced reorganization, shown in tail-to-tail 

 telobiotics with one head excised. 



A. When union is broad, regeneration in one induces 

 reorganization in the other partner, but with considerable delay. 



B. If connection is tenuous, no induced primordium forma- 



tion occurs. (After Tartar, 1958b.) 



2. Timing the period of activation 



When a late stage-4 regenerator is grafted to a smaller non- 

 differentiating stentor, there is usually the transient induction 

 of a beginning reorganization primordium; but the regenerator 



