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. 
Vv. 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 
(autolytic?) processes which can be inhibited through poisons 
such as KCN.’ 
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 Logs AND LEwIs, American Journal of Physiology, Vol. VI (1902), p. 305. 
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