"Activation of the Egg by Bases 157 



formation. We shall see later that bases cause the swelling 

 and liquefaction of the gelatinous mass (the so-called chorion) 

 which surrounds the immature egg of a mollusc, Lottia, and that 

 this action of bases is inhibited by lack of oxygen and by the 

 addition of KCN.' This year the author convinced himself 

 that weak bases like the amines and NH4OH bring about the 

 dissolution of the chorion of Lottia much more rapidly than 

 the strong bases NaOH and tetraethylammoniumhydroxide. 

 It is possible that the induction of artificial parthenogenesis 

 in the sea-urchin egg by bases depends upon the occurrence of 

 a similar process in the cortical layer of this egg. We may 

 imagine that the bases act by accelerating the rate of oxida- 

 tion of a substance (existing in the cortical layer of the eggs) 

 whereby the membrane formation and consequently the devel- 

 opment of the egg is induced. 



' Loeb, Univeriity of California Publications, Physiology, III, 1, 1905. 



