224 



those quadrupeds also which mostly inhabit the 

 ters, the temperature is quite as high. Dr Martine 

 found the heat of the skin of a sea-calf to be near 

 1O2, and, in the cavity of the abdomen, it was about 

 a division higher *. Such, too, is the case in the 

 cetaceous order of animals, the temperature of the 

 whale and porpoise being as high as that of land ani- 

 mals. In all these animals, the organs of respira- 

 tion and circulation, in their general structure and 

 actions, resemble nearly those of man, with such 

 difference only as the peculiar configuration and 

 modes of life of the animal necessarily introduce. 



1 82. But in birds, which have been stated to pos- 

 sess the highest temperature of all animals, the lungs 

 are differently constituted, and are much larger in 

 proportion to the animal than in other cases. In- 

 stead of lying loosely in the chest, and yielding to its 

 alternate contractions and dilatations as in the mam- 

 malia class, they adhere to the thin transparent mem- 

 brane which covers their lower surface, and performs 

 the office of a diaphragm : besides this attachment, 

 they are also connected to the ribs and sides of the 

 vertebrae. In the larger cavities of the body, and in 

 the interstices about the breast and axilla, are placed 

 air-bags of different sizes, some of which communi- 

 cate immediately with each other, and all may be 

 said to have a communication by means of the lungs. 

 The bones also, which, in other animals, are filled 

 with medullary matter, are, in birds, receptacles for 

 air. Some of these, as the sternum, ribs, and verte- 



* On Thermometers, p. 146. 



