XXX 



PRESERVATION OF THE LIFE OF THE EGG BY THE ACT 



OF FERTILIZATION 



1. The unfertilized egg dies in a comparatively short time, 

 while the act of fertilization saves the life of the egg and allows 

 it to give rise, theoretically at least, to an unlimited series of 

 generations. The question arises : How does the spermatozoon 

 save the life of the egg ? It is not necessary to emphasize the 

 physiological importance of this feature of the process of ferti- 

 lization. 



The rapidity with which the unfertilized eggs die differs 

 according to the species. The unfertilized egg of the starfish 

 (Asterias) dies at summer temperature in a few hours, that of 

 Polynoe in less than a day, while that of the sea-urchin (Arbaria) 

 may live for a week or longer. In all cases the life of the 

 unfertilized egg can be prolonged if its oxidations are suppressed; 

 and the rapidity with which they die seems to depend upon the 

 relative velocity of oxidations in the unfertilized egg. 



As already mentioned, the eggs of the starfish are mostly 

 unripe when laid, and they only begin to ripen in sea-water. 

 The different eggs, however, do not all ripen at the same rate. 

 Now I found that if mature eggs were not at once or soon 

 fertilized or caused to develop by chemical means, they quickly 

 disintegrate, i.e., in the course of a few hours. 



The cytoplasm of the living eggs of Asterias is homogeneous 

 and of a light yellowish color. This appearance the eggs also 

 retain after maturation, as long as they are alive; nor do they 

 lose it if development is initiated by the entry of a spermatozoon 

 or by the methods of artificial parthenogenesis. 



If, however, the ripe eggs remain unfertilized or are not 

 caused to develop, they die in the course of from four to twelve 



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