ASCARIS 



187 



the two nuclei are absolutely identical in appearance (Fig. 85, C). The 

 two nuclei gradually approach one another, the centrosome surrounded 



-AT-. 



FIG. 85. 



Diagram illustrating syngamy in A scaris megalocephala. A, Commencing fusion of microgamete 

 with the egg before formation of polar bodies ; B, formation of second polar body ; C, two 

 gamete nuclei alike, each chromosome drawn out into a long thread ; D, shortening of chromosomes, 

 separation of centrosomes ; E, mitotic spindle with split chromosomes ; F, division of zygote into two 

 daughter cells. M, Macrogamete ; m, microgamete ; N, egg nucleus ; n, sperm nucleus ; II, second 

 polar body. 



by an area of deeply staining cytoplasm lying between them. The 

 centrosome divides into two the two gradually receding from one another. 

 Meanwhile the two chromosomes of each nucleus become greatly shortened 



