738 STUDIES IN GENERAL PHYSIOLOGY 



absolute or relatively high lack of oxygen, were nearly all 

 living! This observation seems to show that the same 

 processes which lead to the maturation of the egg bring 

 about its death if they are not inhibited at the right time. 

 In this way the process of fertilization becomes a life-saving 

 or life -prolonging act. 



V. DO THESE FACTS HOLD FOR OTHER FORMS? 



The question of the relation between maturation and 

 natural death can be studied most beautifully in the starfish 

 egg because it is possible to obtain it in an immature condi- 

 tion, and because maturation follows very rapidly. With 

 sea-urchin eggs conditions are much less favorable since the 

 egg maturates within the ovary, and since it is difficult to 

 obtain immature eggs during the spawning season. I have, 

 therefore, been unable to discover which chemical factors 

 determine the maturation of the sea-urchin egg, and to decide 

 whether the same circumstances cause the death of the sea- 

 urchin egg that bring about the death of the starfish egg; 

 and whether the life of the sea-urchin egg can be prolonged 

 through a prevention of these circumstances. In an indi- 

 rect way Lewis and I attempted to answer this question last 

 year when we assumed that the destructive processes which 

 bring about the death of the unfertilized egg are enzymatic 

 (autoly tic ?) processes which can be inhibited through poisons 

 such as KCN. 1 



We did in fact succeed in showing that the addition of a 

 small amount of KCN to the unfertilized sea-urchin eggs mark- 

 edly lengthens their life. Even after seven days such eggs 

 can be fertilized as soon as they are returned to normal sea- 

 water. We also pointed out that, because of the well-known 

 bactericidal properties of potassium cyanide, the experiments 

 on sea-urchin eggs were not in themselves decisive, and so 



1 LOEB AND LEWIS, American Journal of Physiology, Vol. VI (1902), p. 305. 



