NUCLEOPLASMIC RELATIONS IN ARCELLA / 



described in the first experiment, in so far as it indicates that the 

 size of the immediate progeny is, at least in part, dependent 

 upon the amount of cytoplasm in the parent. By the fourth 

 generation (table 1) the specimens in line 150.2a had reached a 

 mean spine number approximately equal to that of line 150.2b 

 and were rapidly approaching the latter in diameter. This sug- 



B 



8 



Figs. 7 and 8 Arcella dentata. Specimens of family 150. ,4 is one-half of a 

 binucleate specimen; B, its first offspring, and C, the first offspring of the suc- 

 ceeding generation. The normal shape is usually regained in the second genera- 

 tion. X 207. 



gests that the nuclei and cytoplasm in the two lines were quali- 

 tatively alike and that their interaction was such as to lead 

 gradually to the production of specimens in which an equilibrium 

 between the nuclear and cytoplasm masses was regained, thus 

 resulting in specimens similar as regards spine number and 

 diameter. 



