TOWARD A GENETICS OF STENTOR 317 



disruption of the normal form, resembling the "amorphous 

 phenotype" (see p. 276). The nuclear picture also became 

 abnormal, with nuclear nodes of greatly varying size, atypically 

 located within the cell. 



One special case should be mentioned in detail for the interesting 

 possibilities suggested. Addition of the polymorphus component 

 caused the major coeruleus part to dedifferentiate its original 

 feeding organelles, and when regeneration occurred the oral cilia 

 were at first only half the normal size and never did they group into 

 membranelles. These cilia started and stopped together but there 

 was no metachronal rhythm as when membranelles are present 

 (Fig. 90B). An oral differentiation was obtained which was, however, 

 very different from the normal. 



In these chimeras, the complex appeared at first as if stricken 

 by the shock of incompatibility, and regeneration was often at 

 first abortive or incomplete ; but the specimens then recovered and 

 generally showed good oral redifferentiation, yet with the abnor- 

 malities described often appearing later. One may expect, therefore, 

 that from small additions of one species of Stentor to another, 

 after the manner of transduction, and with greater skill in keeping 

 the specimens alive, very interesting results will emerge. 



Referring again to the combination of coeruleus and niger, it was 

 found that the coeruleus cell was greatly affected by the addition 

 of a relatively small piece of niger cytoplasm (Fig. 91). In only one 

 case was the host able to regenerate and maintain good feeding 

 organelles, for in other tests regeneration was incomplete or not 

 even begun (Tartar, 1956c). These two species are apparently so 

 distantly related that even a small admixture of niger greatly affects 

 the behavior of coeruleus^ including the condition of the macro- 

 nucleus. Conversely, coeruleus caused depigmentation of the niger 

 graft. 



The studies of Hammerling have shown that in the unicellular 

 and uninucleate plant, Acetabularia, the cytoplasm is relatively 

 passive and can elaborate cell structures with the support of any 

 species of nucleus of this genus whidh was tested, and the form is 

 that of the species contributing the nucleus or the nuclear products. 

 For in combinations containing two types of nuclei the form was 

 more like that of the species contributing the most nuclei. If the 

 nuclear contributions were balanced the structures produced were 



