644 THE SPOUTING AND MOVEMENTS OF WHALES. 



limit of depth to which he can venture without danger is 30 meters 

 (98 feet) — that is to say, the pressure of three atmospheres. No mam- 

 mal confined under nine atmospheres and suddenly released has sur- 

 vived this treatment; therefore, 90 meters (295 feet) is a limit which 

 no terrestrial mammal can reach. It may be admitted, however, that 

 the whale is accustomed little by little to depths more and more con- 

 siderable, and in his case to increase the depth he can reach, but it is 

 not possible to believe that he can annihilate entirely the ph3\sical law 

 of solution of gases in liquids proportional to pressure, nor that he 

 can prevent the disengagement of these gases when the pressure ceases. 

 Therefore, in giving to the cetaceans, in view of this supposed adapta- 

 tion, a power three times as great as that of the human organism, we 

 must be close to the truth, I believe, indeed, that this limit of 100 

 meters which I have assigned to the cetaceans is rather exaggerated. 



Second. — The weight: The density of the body of the cetaceans is 

 less than that of the sea water in the right whale and the sperm 

 whale; it is a very little superior in the other cetaceans, which sink 

 when killed. To go down, therefore, it is necessary that the whale 

 should swim to the bottom. Furthermore, the living cetacean carries 

 an enormous quantity of air in its lungs, which tends to make it rise 

 to the surface. 



That being so, one can imagine the effort required of a cetacean to 

 plunge to 1,000 meters. It is an effort so enormous that it certainly 

 surpasses the animal's muscular power. One should not forget that a 

 man, whose body is much denser than that of a whale, has to load 

 himself with a very considerable weight when he wishes to dive into 

 the sea to depths which exceed a few meters. . I recall that the cos- 

 tume of a diver weighs 80 kilograms. This is another consideration 

 which prevents me from believing in the 1,000 meters of Kiikenthal. 



Third. — LigJit: We know that the light of day does not penetrate 

 deeper than 300 meters (984 feet) and that, furthermore, at this depth 

 only the chemical rays of the spectrum make their effect felt. One 

 may say, indeed, that practically, for the ej^e of a mammal, the illumi- 

 nated zone does not pass 50 or 60 meters. If sight is unnecessary to 

 the cetaceans which feed upon the plancton, it must, on the contrary, 

 be indispensable to those which feed on fish and cephalopod mollusks. 

 What would the}^ do, then, in the depths l)eyond the limit of illumi- 

 nation that can be utilized ? 



Fourtli. — Food: Whales do not dive for pleasure, they dive in search 

 of food. But what could they find at 1,000 meters i' The fishes on the 

 banks scarcely inhabit great depths, and the zone where the plancton 

 is very abundant — that in which the crustaceans live which serve as 

 food is the zone of the diatoms, that is, the illuminated zone — extends 

 to about loo meters. That there is plancton below this zone is not 



