XXXII 



CAN AX EMBRYO DEVELOP FROM A SPERMATOZOON? 



Leeuwenhook, the discoverer of the spermatozoon, IKK! the 

 idea that it was the future embryo. According to this the egg 

 was only the nutritive medium on which the spermatozoon 

 would develop into the embryo. The observations on natural 

 and artificial parthenogenesis have put an end to such a view. 



It had been shown by Boveri and confirmed by others, 

 especially Delage, that if an unfertilized egg be divided into 

 two fragments, the one with, the other without, a nucleus, 

 the enucleated fragment can also develop if a spermatozoon 

 enters. This case of development of an enucleated fragment 

 of egg protoplasm with a spermatozoon has been utilized to 

 revive the idea that the egg was only the nutritive medium for 

 the development of the spermatozoon. Against such a con- 

 clusion may be urged the fact established, especially by the 

 work of E. B. Wilson, Conklin, R. Lillie, and others, that the 

 protoplasm of the egg and not its nucleus is the embryo and 

 that the protoplasm of the unfertilized egg may be considered 

 a rough preformation of the later embryo. The entrance of a 

 spermatozoon into an enucleated fragment of an egg would 

 simply cause the fragment to run its course of development 

 instead of undergoing the early disintegration to which it would 

 otherwise be doomed. 



Nevertheless the question remains whether it might not 

 after all be possible to raise an embryo from a spermatozoon, if 

 the latter were transferred to a suitable medium. 



J. de Meyer investigated the question whether it is neces- 

 sary that the spermatozoon should come in contact with the 

 cytoplasm of the egg in order to undergo the first phases of its 

 normal evolution. 1 He used the sperm of Echinus microtnlx r- 



i J. de Meyer, Arch, de Bioloyie, XXVI, <if>, 1911. 



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