TEXT-BOOK OF EMBRYOLOGY. 



ozoon must enter, this being of the nature of a channel through the membrane 

 the micropyle. In some instances a little cone-shaped projection from the 



d 



FIG. 23. Fertilization of the ovum of Thalassema. Griffin 

 S , Male pronucleus, **, female pronucleus. 



surface of the egg, the attraction cone (Fig. 22, i), either precedes or imme- 

 diately follows the attachment of the spermatozoon to the egg. Instead of a 

 projection there may be a depression at the point of entrance. 



