52 COMPARATIVE ANATOMY 



nicate freely with each other, but each may be 

 followed to a gi'eat extent, and unravelled, as if 

 twisted upon itself; and, upon the whole, we are 

 free to allow that the suggestion of its use above 

 afforded, presents itself to our view, as alike plau- 

 sible, simple, and satisfactory. 



Mr. Hunter moreover remarked that the quan- 

 tity of blood belonging to the whale tribe is pro- 

 portionably very large, a circumstance which this 

 reservoir at once explains; and M. Desmoulins 

 states, that in the Cetacea the blood is at a higher 

 temperature than in the terrestrial mammalia, rising 

 as high as 104*^. C^ict. Class. d'Hist. Nat.) Re- 

 specting the Lungs., J. Hunter has also observed 

 that they are more than usually elastic ; the pulmo- 

 nary cells, too, are unusually small, and commimi- 

 cate with each other in a way that is not generally 

 seen, for by blowing into one branch of the trachea, 

 not only the lobe to which the air directly goes, 

 but the whole lungs, are inflated. {lb. 418.) 



When we reflect, that in the Cetacea, respiration 

 is carried on through the lungs, and that they 

 inhabit the ocean, we shall at once perceive that a 

 peculiar apparatus must be provided for the per- 

 formance of this function. They have no nostrils, 

 accurately so called, and their mouths are seldom 

 opened in free air, and therefore the process is 

 carried on by tubes which open on the summit 

 of their head, and which are called the blow-holes 

 or spiracles. In man and the other mammalia, 

 the mouth and nostrils, as every one knows, termi- 



