The Development of the Egg. 



121 



velocity of chemical reactions and not to a difference in permeability. 



(b) The action of alkali. — Sodium hydroxide injures or destroys 

 the fertilized egg much more rapidly than the unfertilized egg. 

 The experiments with neutral red mentioned in the previous paper 

 indicate that this base diffuses equally well into the fertilized and 

 the unfertilized egg but that in the former it enters into chemical 

 combination, while in the latter it remains in solution. It can be 

 shown that the toxic action of a comparatively high concentration 

 of sodium hyroxide (e. g. N/500) upon the unfertilized egg can 

 be enormously reduced through the addition of a trace of potas- 

 sium cyanide, while in the fertilized egg the protective effect of 

 potassium cyanide or lack of oxygen is equally noticeable, but 

 for weaker concentrations of sodium hydroxide. 



(c) The action of acids. — It was found that unfertilized eggs 

 are killed by acids as rapidly as fertilized eggs. 



All my attempts to show that the process of membrane forma- 

 tion causes the development of the egg by increasing its permea- 

 bility have thus far met with negative results. 



It is, however, possible to account in another way for the fact 

 that the cytolysis of the cortical layer of the cytoplasm starts the 

 development of the egg. In the process of cytolysis certain sub- 

 stances which were solid are liquefied and enabled to diffuse into 

 the egg. If it could be shown that these substances were of such 

 a nature as to start or accelerate the chemical processes under- 

 lying development the connection between membrane formation 

 and causation of development would become intelligible. 



