THE ARCTIC SEAS. ]47 



is to renew the vital qualities of the blood by 

 presenting it to the air, the oxygen in which uniting 

 with the blood renders it again fit for sustaining 

 life. But if more blood could be oxygenized at once 

 than is wanted for immediate use, and the overplus 

 deposited in a reservoir until wanted, respiration 

 could be dispensed with for a while. This is actually 

 what the wisdom of God has contrived in the Whale. 

 The exhausted blood, which is returned by the veins, 

 having been renewed by its communication with the 

 air in the lungs, is carried to the heart, whence only 

 a part is carried away into the system, the remainder 

 being received into a great irregular reservoir^ con- 

 sisting of a complicated series of arteries, which first 

 lines a large portion of the interior of the chest, then 

 insinuating itself between the ribs, forms a large 

 cushion outside of them near the spine, and also 

 within the spinal tube, and even within the skull. 

 The blood thus reserved is poured into the system 

 as it is needed, and thus prevents the necessity of 

 frequent access to the surface. 



It is an object of importance that the act of breath- 

 ing should be performed with as little effort as possible, 

 and therefore the windpipe is made to terminate 

 not in the mouth, nor in nostrils placed at the 

 extremity of the muzzle. If this were the case it 

 would require a large portion of the head and body to 

 be projected from the water, or else that the animal 

 should throw itself into a perpendicular position; 

 either of which alternatives would be inconvenient 

 when swimming rapidly, as, for example, endeavouring 

 to escape when harpooned. The windpipe, there- 



