WHALES. 219 



but destitute of medullary cavity or marrow. The fat 

 probably answers another purpose, that of preserving 

 the body of the animal from the effect of pressure when 

 it descends to the immense depths, to which it some- 

 times plunges perpendicularly. 



The respiration of the whale tribe is one of the 

 most singular parts of their economy. They must feed 

 in the water, and the balcente, or common whales, must, 

 from the size of their bodies, and the smallness of their 

 gullet, which admits a hen's egg with difficulty, spend a 

 great deal of time in that operation ; so that breathing 

 by the mouth would be very inconvenient. Instead of 

 this, the blow-holes, or openings through which the 

 whale breathes, are on the very highest part of the 

 head ; and as in land animals the mouth is made to 

 assist the nostrils in the function of breathing, so the 

 nose in whales is made to assist the mouth in the dis- 

 charge of that part of the water, which, from the rapidity 

 of its motion, cannot so easily escape by the gape of 

 the jaws. 



In all the tribe, there are two openings leading from 

 the back part of the mouth to the top of the head ; 

 but in many of the species, there is only one ex- 

 ternal opening, though in the common whales there 

 be two. At the top of the larynx, there are two 

 tubes of the gullet in these animals, one of which goes 

 to the cavities of the head, into which the blow-holes 

 open, and the other to the mouth. The larynx opens 

 into the former, but is so formed, that it cannot be 

 opened by pressure from without, so that any watei 

 which gets so far into the gullet, is forced up into the 

 cavities in the head. The tubes which lead to those 



