CHAPTER V 



ARTIFICIAL PARTHENOGENESIS 



I. The majority of eggs cannot develop unless they 

 are fertilized, that is to say, unless a spermatozoon 

 enters into the egg. The question arises: How does 

 the spermatozoon cause the egg to develop into a new 

 organism? The spermatozoon is a living organism 

 with a complicated structure and it is impossible to 

 explain the causation of the development of the egg 

 from the structure of the spermatozoon. No progress 

 was possible in this field until ways were found to 

 replace the action of the living spermatozoon by well- 

 known physicochemical agencies. 1 Various observers 

 such as Tichomiroff, R. Hertwig, and T. H. Morgan 

 had found that unfertilized eggs may begin to segment 

 under certain conditions, but such eggs always disin- 

 tegrated in their experiments without giving rise to 

 larvae. In 1899 the writer succeeded in causing the 



1 The substitution of well-known physicochemical agencies for the 

 mysterious action of the spermatozoon was the task the writer set 

 himself in this work and not the explanation of natural parthenogenesis, 

 as the author of a recent text-book seems to assume. 



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