Manchester Memoirs, Vol. Ixii. (1917), No. 2 37 



they appear to " transfer the problem of fertilisation from the 

 realm of morphology into the realm of physical chemistry." 

 This, I think, is only partially true, for though various agents 

 have the power of calling into play (the latent capacity for seg- 

 mentation resident in the ovum k it does not follow that the action 

 of the sperm is identical with thajt of any of these agents. In- 

 deed, it may well be tha;t the stimulus supplied by the sperm is 

 peculiar to itself, and that the substances employed in the ex- 

 periments produce the same effect by entirely different means. 

 It seems to me significant that few, if any, animals have been raised to 

 sexual maturity by these artificial means, and I would suggest 

 that this may be accounted for by (the fact that the chromatin 

 of the male element is lacking" in these cases, which have not 

 become so modified as to develop perfectly with half the amount 

 of nuclear matter characteristic of the species, as have a few 

 naturally parthenogenetic eggs such as those which produce the 

 male bees. 



[While this paper has been passing through the press I have heard that 

 Loeb has recently been able to obtain male and female frogs by 

 artificial parthenogenesis, but whether these animals are capable 

 of producing functional spermatozoa and ova I am not able to say.] 



