ARTIFICIAL PRODUCTION OF NORMAL LARV.E 623 



the egg, either by its carrying specific ions into the egg or 

 by carrying enzymes, or in some other way which is as yet 

 unknown to us. It is certainly remarkable that the sperma- 

 tozoa contain a large amount of ash (5 per cent., according 

 to Hammarsten). In the partheiiogenetic egg the colloids 

 are from the beginning in such a condition as to allow the 

 development to proceed. In other animals it is perhaps 

 solely the ion constitution of the sea-water or of the blood 

 which prevents the eggs from developing parthenogenetic- 

 ally. I shall discuss this point more fully in connection 

 with further experiments on this subject. 



