192 



THE BIOLOGY OF STENTOR 



Fig. 52. Exceptions to formation of primordium in association 

 with a locus of stripe-width contrast. 



A. Anterior half of a stentor, with intact feeding organelles, 

 was grafted to two minced stentors. Next day two division 

 anlagen were formed, one in the l.s.c. and another (jc), paradoxi- 

 cally, amidst medium-width striping. 



B. Specimen resulting from rotating anterior half 90° on the 

 posterior developed primordium only in the minor l.s.c. 



C. Fifth day reorganization in a regenerator to which an 

 additional regeneration primordium had been grafted. 

 Secondary anlage (x) appeared where a primordium site had 



been but which no longer showed contrasting stripe areas. 



D. Regeneration in posterior tip cut from a stage-2 divider, 

 the anlage appearing in a site of negligible contrast in stripe 



widths. 



E. Anterior aboral corner fragment of a coeruleus bearing 

 anlage without significant l.s.c. but showing some branching of 

 striping. Later normal primordium site was formed by further 



stripe multiplication. 



F. Tiny fragment with regeneration primordium developing 

 amidst a few uniform granular stripes. Stomatogenesis did not 



occur and the specimen died 2 days later. 



