XXXII 
CAN AN EMBRYO DEVELOP FROM A SPERMATOZOON ? 
Leeuwenhoek, the discoverer of the spermatozoon, had 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.!. He used the sperm of EHchinus microtuber- 
1J. de Meyer, Arch. de Biologie, X XVI, 65, 1911. 
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