THE PROBLEM OF ACTIVATION 229 







In the next year I attempted to show that the pres- 

 ence of the agglutinating substance is necessary for 

 activation in the sea urchin, basing the argument upon 

 three classes of facts: (i) Fertilized eggs, which are of 

 course incapable of reactivation, produce no more of 

 this substance, which disappears at the moment of ferti- 

 lization. (2) Eggs activated by butyric acid, which 

 are incapable of fertilization, likewise produce no more 

 of it. (3) If eggs are subjected to repeated washings 

 their production of this substance gradually declines, 

 and along with it the capacity for fertilization also. 

 To the last point Loeb has objected that the general 

 vitality of the eggs is also declining under these circum- 

 stances; while this may be so in the case of the first 

 experiments that I performed, the objection does not 

 apply with equal force to other experiments in which 

 the protecting jelly of the eggs was first removed by 

 shaking before beginning the series of washings; under 

 these circumstances the parallel loss of agglutinating 

 power and of capacity for fertilization went on much 

 more rapidly. 



Moore (1916) has also found a parallel loss of agglu- 

 tinating power and of capacity for fertilization in 

 Arbacia by graded butyric acid treatment for partheno- 

 genesis. He has also shown that eggs exposed to a 

 temperature of 35 C. lose their agglutinating power and 

 their capacity for fertilization simultaneously. It re- 

 quires a temperature of about 41 C. to cause cytolysis 

 in these eggs, and the evidence is that exposure to 

 35 C. does not destroy their general vitality; they 

 remain intact for a long period and, if inseminated, 

 are penetrated by the spermatozoa, which, however, 



