THE SECRETS OF THE SEA 331 



No doubt there are very many forms that all our 

 labor has failed to bring to light, but readily find- 

 able if only we could go among them ; but we shall 

 never be able to do this. The pressure of the 

 water down there is so great it would crush any 

 apparatus we could devise to protect us. Inves- 

 tigators differ as to the depth to which the light of 

 the sun penetrates into the sea, some saying it is 

 less than a hundred fathoms and others that it 

 is twice that. Much depends, no doubt, on the 

 clearness of the water and the directness of the 

 sun's rays, but it is probable that at one hundred 

 and fifty fathoms, the greatest depth at which we 

 dredged, there is either total darkness or merely 

 the faintest twilight at noonday. 



One naturally wonders how it is possible so 

 amazing a quantity and variety of animal life can 

 exist in a region so cold and dark and below the 

 limit of plant existence. On the Pourtales Plateau 

 there is an overwhelming abundance of food, for 

 the region lies just at the Tropic of Cancer, and as 

 Grant Allen has remarked, "The tropics are bio- 

 logical headquarters." The Gulf Stream sweeps 

 over it constantly bringing pure, warm water 

 literally swarming with minute life. Most of this 



