THE PHYSIOLOGY OF FERTILIZATION 165 



are put into a solution which prevents their develop- 

 ment (sea-water with chloral hydrate or NaCN) when 

 taken out they behave as though nothing had happened 

 to them. He considers this a demonstration that arti- 

 ficial activation can be reversed. Now it is notable 

 that in such treatment no visible change occurs in the 

 alkali, but only after transfer to sea-water. It would 

 seem then to be a reasonable interpretation that such 

 changes are prevented by the chloral or NaCN. What 

 is reversed therefore in this case is at most a condition 

 which permits of cortical changes in sea-water. If the 

 eggs are placed from the alkali in sea-water, even if 

 only for a few minutes, before the chloral or NaCN 

 sea- water, they will not " reverse." 



It is apparent that such results can be as readily 

 understood in the quantitative sense of partial or arrested 

 activation as in terms of reversal. The fertilization 

 reaction has definite quantitative relations, as we have 

 seen in discussing partial fertilization; the same is true 

 of any part of the series of reactions, and it certainly 

 holds for the cortical reactions in activation. If, there- 

 fore, the cortical reactions are incomplete in any experi- 

 ment the possibility of superimposing fertilization on 

 such incomplete reactions might remain. 



C. R. Moore (1916) has shown in experiments con- 

 ducted under the writer's observation that such a quan- 

 titative relation actually obtains. To understand the 

 experiments and results it is essential to examine the char- 

 acter of artificial activation by means of butyric acid, 

 which was the agent used in both Loeb's and Moore's ex- 

 periments. The strength of the acid and time of exposure 

 are variable factors. Fifty c.c. sea-water +2.8 c.c. N/io 



