DEATH AND PROLONGATION OF LIFE IN THE EGG 203 



2.5 m NaCl) afterwards, the eggs of purpuratus need remain in 

 the solution for only from forty to sixty minutes. If, however, 

 the eggs are put into the hypertonic solution first and submitted 

 to the treatment for membrane formation (e.g., butyric acid 

 treatment) afterwards, they must remain in the hypertonic solu- 

 tion from 90 to 150 minutes. In the case of *the egg of Arbacia 

 this treatment in itself would induce artificial parthenogenesis, 

 but in the egg of Strongylocentrotus purpuratus it does in most 

 cases leave the eggs either intact or causes them to segment 

 once or a few times and then to go into a state of rest again. 

 When such eggs are afterwards treated with butyric acid they 

 will develop. 



The reason why the eggs must remain longer in the hypertonic 

 solution when this treatment precedes the artificial membrane 

 formation, than when it follows, seems clear if we consider the 

 fact that the corrective effect of the hypertonic solution is weak- 

 ened or inhibited if we inhibit or diminish the oxidations in the 

 egg. This indicates that the corrective effect is in some way con- 

 nected with the formation of a product of oxidation in the egg 

 which is not formed in normal sea water. Since the rate of oxi- 

 dations is from four to six times as great in the egg after the mem- 

 brane formation as it is before, we can understand why the hyper- 

 tonic solution brings about the corrective effect so much more 

 quickly in the egg after membrane formation than before. 



4. Working on the idea that the corrective effect of the hyper- 

 tonic solution was due to the formation of a specific oxidation 

 product in the egg it occurred to the writer to test whether the 

 corrective effect of the hypertonic solution was reversible or per- 

 manent. Unfertilized eggs of S. purpuratus in which no mem- 

 brane formation had been called forth were treated with a hyper- 

 tonic solution and then portions of these eggs were treated after 

 varying intervals of from one hour to three days with butyric 

 acid. In all cases the butyric acid treatment now sufficed to call 

 forth in these eggs a normal development at any time. This 

 shows that the corrective effect produced by the hypertonic so- 

 lution is irreversible and lasts in the egg as long as the latter 

 lives. 



