NUCLEOPLASMIC RELATIONS IN ARCELLA 



21 



The principal differences between specimens that have been 

 deprived of one nucleus and those from which one nucleus 

 plus half of the cytoplasm has been removed, seem to be due 

 to the larger amount of cytoplasm in the former. The nucleus 

 and cytoplasm remaining in the latter are able to build up 

 within three or four generations a new imcleus and an equal 

 amount of cytoplasm, thus regaining the original condition, 

 whereas in specimens from which one nucleus alone has been 

 removed, the offspring are larger because of the large amount 

 of cytoplasm in the operated parent and nuclear doubling is 

 hastened, probably being initiated by the inequality between 

 the single nucleus and the cytoplasmic mass. 



13-27 8 



13-28(1)- 



-14-33(2): 



-16-34(2) 

 -15-35(2) 



~13-32(2) 



-14-34(2) 



15-34 



12-28 E 



14-33(2) 



^14-33(2) 



Fig. 19 Arcella dentata. Pedigree of part of the specimens reared in one of 

 the microdissection experiments (exp. 3). 



Another series of microdissection experiments consisted in 

 the removal of parts of the nucleus of uninucleates. Opera- 

 tions of this kind were successful, but the patient died in every 

 case. These results are striking when contrasted with those 

 obtained by the removal of cytoplasm, described in the following 

 paragraphs. 



b. Experiments on uninucleate specimens of family 150 



These experiments were designed to test further the per- 

 sistence of the relations between nuclei, cytoplasm, and shell 

 characteristics in family 150. Operations were performed 



