NUCLEOPLASMIC RELATIONS IN ARCELLA 33 



or four generations the diameter and spine number of the orig- 

 inal line before the cutting operation was performed are 

 regained. This procedure proves that in these organisms a 

 marked change in the condition of the germ plasm (the change 

 from the uninucleate to the binucleate state) is not imme- 

 diately expressed in full by the somatoplasm, but that several 

 generations are required for complete adjustment. As in the 

 case of the uninucleates described in paragraph 5, the gradual 

 assumption of the normal characteristics of the binucleates of 

 the family is probably due to the fact that the capacity of the 

 shell limits the quantity of cytoplasm and hence prevents the 

 attainment of the complete size in one generation. 



8. Empty shells were produced by several binucleate speci- 

 mens, but this process did not lead to an increase in the number 

 of nuclei, and no modifications of the cytoplasm or shell charac- 

 teristics were noted in the later offspring. 



9. Diameter and spine number are closely correlated in both 

 binucleates and uninucleates; the coefficient for the binucleates 

 is 0.640 ± 0.027 and that for the uninucleates 0.402 ± 0.039. 



10. In several cases changes from the binucleate to the uni- 

 nucleate condition occurred. The uninucleate parents and 

 progeny later regained the binucleate condition during empty 

 shell formation. Hypotheses are presented to account for 

 these changes. 



11. Nucleated pieces of bisected uninucleate specimens con- 

 tinue to live and reproduce, giving rise to offspring smaller than 

 the original parent. These offspring produce larger uninu- 

 cleate specimens and these in turn form larger offspring until 

 after three or four generations the normal diameter and spine 

 number of the uninucleates of the family are regained. 



12. The bisection of uninucleates belonging to five succeeding 

 lines had no permanent influence upon the characteristics of 

 the family, since in every case the normal characteristics of 

 the uninucleates were regained; empty shell formation occurred, 

 and binucleates like those of the original line were finally pro- 

 duced. In one line no empty shells nor binucleates were re- 

 corded, but this was no doubt because the line was not kept 

 long enough. 



