TOWARD A GENETICS OF STENTOR 



313 



Interactions between S. coeruleus and Stentor X, 



which was either a closely related species or a dwarf race. 



a: S. coeruleus. b: Stentor X, of about \ volume of former, 

 fewer stripes, and smaller macronuclear nodes, a' : X-nuclei 

 implanted into enucleated coeruleus gives complete regeneration 

 {a") but mouthparts resorption and death soon follow {a"'). 



b-b'" : Similarly for the reciprocal cross. Feeding organelles 

 are in proportion to size of the cytosome in which they are formed. 



ab : Graft of the 2 forms undergoes simultaneous reorganiza- 

 tion and integrates the two shapes into a doublet {ab') but the 

 specimen then died. (After Tartar, 1956c.) 



by some subtle and possibly immunological difference which 

 resulted in eventual malfunctioning. The general picture suggested 

 is that nucleus and cytoplasm no doubt have respective roles in the 

 act of cytodifferentiation which are the same in all species, but that 

 the specific adaptation of the one to the other is developed to such 

 a degree that sooner or later a disharmony will almost always 

 emerge to nullify whatever compatibilities were at first realized. 

 Initially it appeared that polymorphus macronucleus could not 

 support regeneration in coeruleus cytoplasm (Tartar, 1953), but 

 further tests (1956c) showed that primordium formation at least 

 is possible (Fig. 89A). Typically, an anlage was produced which 

 progressed to stage 4 and then was resorbed. Hence there was some 

 effective interaction, but not as much as in the first combination 

 described. In regard to other combinations, it was found that 

 neither roeseli nor niger nucleus supported regeneration in coeruleus, 

 but there was one positive result with introversus nucleus which 

 after 5 days finally led to satisfactory oral differentiation in 



