ITS RESPIRATORY APPARATUS. 355 



the animal ; but as its specific gravity is actually less than 

 that of the ocean- waters, instead of being a burden and 

 an incumbrance, it is a help, it buoys up the whale's 

 colossal bulk, renders it relatively lighter, and largely 

 increases its activity. 



We proceed to some other characteristics of the whale. 



Its flesh is described as more nearly resembling that of 

 beasts than of fish ; it is firm, solid, somewhat coarse, and 

 in flavour not unlike indifferent beef. The osseous struc- 

 ture also reminds the anatomist of a terrestrial quadruped. 

 The milk of the female is very rich ; like cow's milk to 

 which cream has been added. 



A remarkable circumstance connected with the vital 

 economy of the whales, is the long period during which 

 they can suspend the respiratory function. In the mam- 

 mals generally the inhalations succeed each other with 

 great rapidity, and the interval between each is never 

 more than a few moments. Man, even when at rest, 

 breathes every three seconds ; but the Cetacea can sus- 

 pend their inhalations, or, in more popular language, 

 " hold their breath," for an hour or even two hours, and 

 thus are enabled to remain under water for a considerable 

 period without inconvenience. 



All fishes separate the air from the water by means of 

 their gills ; but the whale, having the respiratory apparatus 

 of the mammal, must draw his supply of air from the at- 

 mosphere, and hence must frequently come to the surface 

 to breathe. He has, however, no nostrils properly so 

 called, and seldom opens his mouth in free air. How, 

 then, does he manage to breathe ? By tubes opening 

 nearly on the crown of the head, called spiracles or blow- 



