FOOD. 245 



respiration be kept up. Cooled down to 64 F., they can- 

 not recover unless external warmth be applied together 

 with the employment of artificial respiration. Rabbits 

 not cooled below 77 F. recover by external warmth 

 alone. 



CHAPTER IX. 



DIGESTION. 



DIGESTION is the process by which those parts of our 

 food which may be employed in the formation and repair 

 of the tissues, or in the production of heat, are made fit to 

 be absorbed and added to the blood. 



Food. 



Food may be considered in its relation to these two pur- 

 poses the nutrition of the tissues, and the production of 

 heat. But, under the first of these heads will be included 

 many other allied functions, as, for example, secretion and 

 generation : and under the second, not the production of 

 heat only as such, but of all the other forces correlated 

 with it, which are manifested by the living body. 



The following is a convenient tabular classification of 

 the usual and more necessary kinds of food : 



NITROGENOUS : 



Proteids, as Albumen, Casein, Syntonin, Gluten, and their allies, 

 and Gelatin ; (containing Carbon, Hydrogen, Oxygen, and Nitrogen ; 

 some of them, also Sulphur and Phosphorus). 



NoN-NlTKOGENOTJS : 



(i). Amyloids Starch, Sugar, and their allies (containing Carbon, 

 Hydrogen and Oxygen). 



(2). Oils and Fats (containing Carbon, Hydrogen, and Oxygen ; the 

 oxygen in much smaller proportion than in starch or sugar). 



(3). Mineral or Saline Matters ; as Chloride of Sodium, Phosphate of 

 Lime, etc. 



(4). Water. 



