MAMMIPEROUS ANIMALS. 33 



tlfem the vital air and the matter of heat, are sepa- 

 rated, the former containing the only principle 

 proper for the maintenance of life, and the latter 

 being necessary towards keeping up the fluidity of 

 the blood. The mephitic air, which remains after 

 the separation, is immediately expired. This act 

 of drawing in the atmospheric air, separating the 

 vital air, and matter of heat, and ejecting the me- 

 phitic air, is termed respiration. 



In digestion it is that the juices calculated to nou- 

 rish and support the body become separated from the 

 other less useful parts of the food. Reduced to a 

 pulp by means of the teeth and saliva, this is thrown 

 into a canal which, below the thorax, terminates in a 

 large bag or reservoir, called the stomach. Here the 

 aliment, penetrated and further dissolved by new 

 juices, undergoes atriturition from the action of the 

 stomach; and the nutritive juices, which, on their 

 union, are denominated chyle, are now expressed. 

 These are taken up by little vessels called lacteals, 

 and become converted into new blood and fiesh. 

 The alimentary canal again contracts on leaving the 

 stomach, and twisting into a great variety of folds, 

 acquires the name of intestines. The residue of what 

 is not converted into chyle traverses these numicrous 

 canals, and from them is expelled the body. 



The bodies of all Mammilerous Animals are sup- 

 ported by a frame of bones, called a sktklon. To 

 these bones are attached the tiiusclcs or fiesli, assem- 

 blages of fibres held together by membranes, and 

 terminating in a kind of cords called tendons. Ihese 

 muscles, when excited, produce motion in the diffe- 



Vol. I. D 



