212 ESSENTIALS OF ZOOLOGY 



to form the fusion nucleus, and the fertilization is complete. The 

 s^nmrance of fertilization is largely centered around two important 

 functions First, it is the impetus for the development of an embryo 

 omX egg under most normal ci-mstances ; however, par hen - 

 genesis replaces this function in some cases. Secondly, it brings 



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• • • -• •••-•...•. . • • • • . • • 



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F,g 61.-Fertn,zation in the sea. urchin Jo J0P-««-- ,S.n^^^^^^^^^ 



m, fransiormation of ^l-iroi^f °%'" ?S |d by S«™'s= °" ^'°'" °"'Srt "/ ^ 

 °;:,.Sf;rit^^o'SV^Saraif S"'t^ii^y^ i'na son. Inc.. after W.ison., 



about the means for inheritance of characteristics from two different 

 toes of ancestry. This union also restores the diploid number of 



chromosomes. 



