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 NH,OH bring about the 
dissolution of the chorion of Lotttza 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. 
1 Loeb, University of California Publications, Physiology, III, 1, 1905. 
