STUDIES OF FERTILIZATION 587 



THE THEORY OF PARTHENOGENESIS 



A theory of parthenogenesis must also be a theory of fertili- 

 zation, at least for the phenomena common to both. Similarly 

 a theory of fertilization must be consistent with the facts of 

 parthenogenesis. This has been generally recognized and it is 

 one of Loeb's great services to have brought about the recog- 

 nition of this principle and to bring the problem of fertihzation 

 definitely into the field of physiology. That the fertilizin theory 

 is consistent in this respect is sufficiently obvious; indeed it makes 

 the action of the sperm itself into a kind of parthenogenesis, for the 

 sperm activates the fertilizing substance already present in the 

 egg. The egg is self -fertilizing. 



However, it lies beyond the province of this paper to consider 

 the various methods of artificial parthenogenesis in detail and to 

 examine the question of their consistency with the theory. It is 

 obvious, I think, that the fertilizin theory from its very nature 

 :Is more elastic with reference to this problem than any other, and 

 is in general, therefore, more consistent with the established fact 

 of the great variety of proved parthenogenetic agents. 



Obviously it suggests certain lines of experimentation in 

 parthenogenesis. Glaser has already followed one of these fines 

 with some success, viz. : The effect of exposure of eggs to extracts 

 or secretions of eggs of their own species; and he has ascertained 

 that such extracts are rather efficient parthenogenetic agents in 

 the case of Arbacia, especially when followed by treatment with 

 hypertonic sea-water. He did not, however, observe the for- 

 mation of membranes in eggs so treated, which leaves the mechan- 

 ism of action rather obscure; farther analysis of the result is 

 desirable. 



But the whole procedure in experiments in parthenogenesis 

 must take on a different aspect as soon as it is realized that the 

 entire process, and not merely part of it, consists in acceleration 

 of possible combinations in the egg, or increase in avidity of cer- 

 tain chemical groups. 



It is not possible to separate the problem of fertilization from 

 the general problems of cellular physiology; I may therefore be 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 16, XO. 4 



