NUCLEOPLASMIC RELATIONS IN ARCELLA 



31 



of cytoplasm will in a few generations give rise to specimens 

 with the nuclear condition and shell characteristics of the line. 

 3. Lines 156 and 157. These two lines were derived from 

 two specimens taken from the stock being used for selection 

 work in family 58. Fifteen specimens were reared in line 156 

 and 22 specimens in line 157. In both lines the relations 

 between uninucleates, binucleates, empty shells, and the process 

 of nuclear doubling were similar to those observed in the other 

 lines described above. 



Fig. 29 Arcella dentata. Specimens selected from line 155b to show the 

 stages from the original progenitor to the attainment of the normal binucleate 

 condition. A = original progenitor (155b). B = first offspring of A (155bl). 

 C = first offspring of B (155bl.l). D = first offspring of C (155bl.l.l.). E = 

 first offspring of D (155b.l. 1.1.1). This was empty. F = second offspring of D 

 (155b. 1.1.1.2). This was binucleate. G = normal binucleate, being the great 

 granddaughter of F (153b.l.l.l.2.1.1.1). X 207. 



e. Summary of results of experiments on Arcella dentata 



1. When part of the shell is removed there is no regeneration 

 of the missing piece. 



2. When part of the cytoplasm is removed the fi progeny are 

 smaller than the parent, but the parental size is regained in the 

 succeeding generation, thus showing that the size of the off- 

 spring depends in part upon the amount of cytoplasm within 

 the parent, and possibly also upon the capacity of the shell 



THE JOURNAL OP EXPERIMENTAL ZOOLOGT, VOL. 30, NO. 1 



