312 Trans. Acad. Sci. of St. Louis. 



egg toward the nucleus at the point where it lies nearest the 

 surface. The nucleus itself is still inclosed in the cytoplasmic 

 envelope. When it reaches the nuclear membrane it finds or 

 breaks an opening into the egg nucleus, and, escaping from 

 its cytoplasmic covering, passes unchanged into the nucleus of 

 the egg. The cytoplasmic envelope is left in the egg cyto- 

 plasm where it disappears. 



8. The entrance of the sperm nucleus here, as in OycaSy 

 does not increase the size of the ejro: nucleus. 



9. After entering the egg nucleus the sperm nucleus begins 

 at once to assume the "resting stage " by breaking up into 

 the nuclear network or reticulum bearinsf fine chromatin eran- 

 ules. This network is from the first so fused or entangled with 

 the network of the egg nucleus already present that it is im- 

 possible to distinguish any diflerence between the sexual 

 elements in the fertilized egg after the form of the sperma- 

 tozoid disappears. 



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