ASCARIS 



187 



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

 two nuclei gradually approach one another, the centrosome — surrounded 



Fig. 85. 



Diagram illustrating syngamy in Ascaris 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 ; w, nncrogamete ; N, egg nucleus ; n, sperm nucleus ; IT, second 

 polar body. 



by an area of deeply staining cytoplasm — flying between them. The 

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

 Meanwhile the two chromosomes of each nucleus become greatly shortened 



