GERM CELLS IN THE ARTHROPODA 121 
cromatico” (B). This ring passes intact to one of 
the daughter cells (C), whereas the chromosomes are 
Fic. 38.— Differentiation of nurse cells and odcytes in Dytiscus mar- 
ginalis. A. Odgonium with chromatin of nucleus separating into 
two parts. B. Metaphase of odgonial mitosis; the ‘‘ anello croma- 
” 
tico’’ is situated at the lower end of spindle. C. Two-cell stage; 
the lower cell with nucleus containing two sorts of chromatin. 
D. Four-cell stage; ‘‘ anello cromatico’’ in one cell. E. Eight-cell 
stage; cells ready to divide. F. Sixteen-cell stage; one large cell 
(odcyte) with chromatin from the ‘‘anello cromatico,’’ and fifteen 
nursecells. (A-D, F, from Giardina, 1901; E, from Debaiseaux, 1909.) 
equally divided. During the succeeding mitoses 
similar differential divisions occur resulting in one 
odcyte containing the chromatic ring (Fig. 38, F) and 
