GENERAL SKETCH 



133 



Fig. 65. Fertilization of the egg of Ascaris mcgalocephaia, var. bivalens. [BOVERI.] (For 

 later stages see Fig. 104.) 



A. The spermatozoon has entered the egg, its nucleus is shown at d" ; beside it lies the granu- 

 lar mass of "archoplasm" (attraction-sphere); above are the closing phases in the formation of 

 the second polar body (two chromosomes in each nucleus). B. Germ-nuclei (9, o") in tne reticu- 

 lar stage; the attraction-sphere (a) contains the dividing centrosome. C. Chromosomes forming 

 in the germ-nuclei ; the centrosome divided. D. Each germ-nucleus resolved into two chromo- 

 somes ; attraction-sphere (a) double. E. Mitotic figure forming for the first cleavage ; the chro- 

 mosomes (c) already split. F. First cleavage in progress, showing divergence of the daughter- 

 chromosomes towards the spindle-poles (only three chromosomes shown). 



