126 



THE BIOLOGY OF STENTOR 



Fig. 31. Observations relating to proportionality of mouthparts 

 in S. coeruleus. 



A. Regenerator in stage 3 is transected and the halves rotated 

 on each other. Both sections of the as yet undetermined pri- 

 mordium produce mouthparts. Those from the anterior part 

 are very small; posterior anlage almost entirely used to form a 



very large set of mouthparts. Yet — 



B. If the halves of such a specimen are separated, equal, 

 proportionate and medium-sized oral differentiations are 



produced. 



C. From deletions to the primordium site a very short 

 regeneration anlage was produced, forming much too small a 



set of mouthparts for the size of the animal. 



