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 1 



I. INTRODUCTION 



I HAVE pointed out in my earlier publications that fertili- 

 zation of the egg serves to prolong the life of the egg. 2 



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. Ill (1902), p. 295. 



2 Part II, p. 689; LOEB AND LEWIS, American Journal of Physiology, Vol. VI 

 (1902), p. 305. 



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