402 OTTO GLASER. 



I. The Surface-Alteration Theory. The view which we may 

 call the surface-alteration theory is a product of the work of 

 Loeb, R. S. Lillie, and many others. According to Loeb the 

 initiation of development depends in the first place upon a 

 superficial cytolysis, or destruction of the cortical layer of the 

 egg, brought about either by a lysin in the sperm, or by the 

 so-called parthenogenetic methods and agents. After this alter- 

 ation of the surface the rate of oxidation in the egg is raised from 

 four to six times. Loeb says: 



"There are two possibilities by which this result can be pro- 

 duced : either a catalyzer (an oxidase) is carried into the egg by 

 the spermatozoon ; or the change in the surface layer itself causes 

 the increased rate of oxidation. Everything speaks in favor of 

 the second assumption." 1 Further on Loeb suggests "that the 

 spermatozoon causes development ... by removing an obstacle 

 to development." 1 



R. S. Lillie ('u and earlier papers) has suggested that the super- 

 ficial cytolysis increases the permeability of the egg, and further 

 that through this increase in permeability a substance antagon- 

 istic to oxidation is eliminated from the egg. This substance he 

 imagined might be CO 2 ('09). 



Against this idea Loeb has raised objections. Inasmuch as 

 COz "is a good agency for calling forth membrane formation" 

 and as only substances capable of diffusing into the egg can have 

 this effect, the egg surface must be permeable to CO 2 before 

 fertilization, and consequently there can be no accumulation 

 that could be relieved as the result of an increase in permeability. 



This criticism seems valid, and while it constitutes a reason for 

 giving up the idea that the antagonist lost is CO 2 , it in no way 

 bears on the other idea, namely that there is an increase in the 

 permeability of the ovum as the result of fertilization. However 

 this idea also has failed of acceptance by Loeb, but this is due 



1 " Artificial Parthenogenesis and Fertilization," 1913, p. 13. 



2 The obstacle "removed" is a cortical layer unsuited for development, and the 

 "removal" is in reality an alteration of this cortex: "Through cytolysis of the 

 cortical layer of the egg the oxidations in the unfertilized egg are accelerated from 

 four to six times their normal rate" (loc. cit., p. 14). Since this heightened oxida- 

 tion persists after fertilization, and since the permeability of fertilized eggs may 

 not be different from that of unfertilized, it is possible that the cytolysis of the 

 cortical layer alone is insufficient to account for the increase in the rate of oxidation. 



