ii8 Artificial Parthenogenesis 



According to Warburg it is probable that the oxi- 

 dations occur mainly if not exclusively at the surface 

 of the egg since NaOH, which does not diffuse into the 

 egg, raises the rate of oxidations more than NH4OH 

 which does diffuse into the egg. And finally, the same 

 author showed that the oxidations in the sea-urchin 

 egg are due to a catalytic process in which iron acts 

 as a catalyzer.' In view of all these facts and their 

 harmony with the methods of artificial parthenogenesis 

 the suggestion is justifiable that the alteration or 

 cytolysis of the cortical layer of the egg is in some 

 way connected with the increased rate of oxidations. 

 The question remains then : How can membrane for- 

 mation or the alteration of the cortical layer underlying 

 membrane formation cause an increase in the rate of oxi- 

 dations? One possibility is that the iron (or whatever 

 the nature of the catalyzer may be) exists in the cortex 

 of the egg in a masked condition — or in a condition in 

 which it is not able to act — while the alteration of the 

 cortical layer makes the iron active. It might be that 

 either the iron or the oxidizable substrate is contained 

 in the lipoid layer in the unfertilized condition of the egg 

 and that the destruction or cytolysis of the cortical 

 layer brings both the iron and the oxidizable substrate 

 into the watery phase in which they can interact. 



alteration of the cortical layer of the membrane and the corrective 

 effect of the hypertonic solution. The former effect raises the rate of 

 oxidations in the egg, the latter does not. 



' Warburg, O., Sitzngsber. d. Heidelberger Akad. d. Wissnsch., B. 1914. 



