XXXVI 
MATURATION, NATURAL DEATH, AND THE PROLON- 
GATION OF THE LIFE OF UNFERTILIZED STAR- 
FISH EGGS (ASTERIAS FORBESII) AND THEIR 
SIGNIFICANCE FOR THE THEORY OF FERTILIZA- 
TION! 
I, INTRODUCTION 
I HAVE pointed out in my earlier publications that fertili- 
zation of the egg serves to prolong the life of the egg.’ 
The mature unfertilized egg dies in a comparatively short 
time. Because of this fact the egg becomes of importance 
as an object of experiment, to study the question of natural 
death and the prolongation of life. For by no means has it 
been decided that there is a “natural” death. We only 
know that with an increase in age a critical period is reached 
in which every living organism dies under the influence of 
conditions which do not affect a younger organism. It may, 
therefore, be of interest that we are able to show, as I believe, 
that a critical period exists in the life of many eggs in which 
they die a ‘‘natural” death, and that the life of the eggs can, 
during this period, be saved or lengthened only through 
various external conditions. 
The egg of the starfish (Asterias Forbesii) serves as a 
very favorable object of experiment in the study of this 
question. When removed from the ovary this egg is gen- 
erally “immature,” but as soon as it comes in contact with 
sea-water it begins to “‘maturate.” 
Morphologically, the immature state is characterized by 
1 Biological Bulletin, Vol. IIT (1902), p. 295. 
2Part II, p. 689; Lozs anp Lewis, American Journal of Physiology, Vol. VI 
(1902), p. 305. 
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