Influence of Environment on Animals 209 



The writer found the same temperature coefficient for the rate 

 of maturation of the egg of a mollusk (Lottia). 



All these facts prove that the velocity of development of 

 animal life in Arctic regions, where the temperature is near the 

 freezing point of water, must be from two to three times smaller 

 than in regions where the temperature of the ocean is about 

 10° C, and from four to nine times smaller than in seas the 

 temperature of which is about 20° C. It is, therefore, exactly 

 the reverse of what we should expect when authors state that 

 the density of organisms at or near the surfac e of the ocean in 

 polar regions is greater than in more temperate regions. 



The writer believes that this paradox finds its explanation 

 in experiments which he has recently made on the influence 

 of temperature on the duration of life of cold-blooded marine 

 animals. The experiments were made on the fertilized and 

 unfertilized eggs of the sea-urchin, and yielded the result that 

 for the lowering of temperature by 1° C, the duration of life 

 was about doubled. Lowering the temperature by 10 degrees 

 therefore prolongs the life of the organism 2^^, i.e., over a thou- 

 sand times, and a lowering by 20 degrees prolongs it about one 

 million times. Since this prolongation of life is far in excess 

 of the retardation of development through a lowering of 

 temperature, it is obvious that, in spite of the retardation 

 of development in Arctic seas, animal life must be denser 

 there than in temperate or tropical seas. The excessive 

 increase of the duration of life at the poles will necessitate 

 the simultaneous existence of more successive generations of 

 the same species in these regions than in the temperate or 

 tropical regions.^ 



The writer is inclined to believe that these results have 

 some bearing upon a problem which plays an important role 

 in theories of evolution, namely, the cause of natural death. 



1 The high coeflEicient of temperature of the duration of life may possibly only 

 be found near the upper temperature limit for the life of organisms. But this is 

 suflScient for our theory. 



