NUCLEOPLASMIC RELATIONS IN ARCELIiA 



23 



for the uninucleates of the parent line was regained. This may be 

 illustrated as follows: 



D E 



Fig. 21 Arcella dentata. Outlines of a series of uninucleates that were bi- 

 sected in successive generations. A is the fourth offspring of specimen 150.2b. 

 ^ is a specimen from the third generation derived from the nucleated part of 

 specimen A. C is a specimen derived from the nucleated part of specimen B. 

 D is a specimen derived from the nucleated part of specimen C. £J is a specimen 

 derived from the nucleated part of specimen D. X 207. 



Empty shell formation and nuclear doubling: Empty shells were pro- 

 duced by three members of the second generation, the first after having 

 produced three uninucleate progeny, the second after having produced 

 one uninucleate offspring, and the third immediately. In each case 

 nuclear doubling accompanied empty shell formation. 



Binucleate descendants: These were, from the first, larger than the 

 uninucleates and gradually increased in diameter and spine number 

 until, within three or four generations, they regained the condition 

 characteristic of binucleates of the parent line, 150. 



