No. 535] GERM-CELL DETERMINANTS 



391 



5, D, pd.g). A second division results in sixty-four cells ; 

 this number is constant until a late stage in embryonic 

 develo])ment. 



These sixty-four cells have been traced through the 

 early embryonic stages. First they migrate back into 

 the egg through a 4 'pole cell canal" (Fig. 5, C, pc) sit- 



