Experimental Studies on Germinal Localization. 225 



of the anterior, in the latter case one of the posterior ones). A 

 group is thus produced (Figs. 72-73) which, excepting the usually 

 lessened inequality of 2^-^ and 2^', is practically identical with one 

 quadrant of the lower hemisphere in the 64-cell stage (Cf. Figs. 

 4-5). This is followed by a division, sometimes distinctly un- 

 equal, sometimes nearly equal, of the basal to form a cell of the 

 fourth quartet (Fig. 73). 



Fig. VII. 



Isolated 1/8 Basal, Patella; x 250. 



68, isolated basal (a rather small example; cf. Fig. 100); 69, 70, examples 

 of first division; 71, 32/4-cell stage, typical; 72, 56/8-cell stage, typical 2- 

 group, equal divison of 3; 73, 64/8-cell stage, after formation of 4 (in this ex- 

 ample the 2-group has rotated into an abnormal position); 74, product, 24 

 hours, showing two secondary trochoblasts (products of 2i-i) and two feebly 

 ciliated cells (pre-anal cells?). 



