Classification of Feeding Principles. 9 



sumed during respiration, and by this provision the uniform 

 temperature of warm-blooded animals is preserved throughout 

 winter and summer. If it were not for this constant source of 

 heat the bodies of warm-blooded animals would soon become 

 cold and stiff as the bodies of dead animals do. Respiration 

 thus is necessary to supply heat to the animals. 



In recapitulation of the above remarks it may be briefly 

 stated : 



1. The earthy substances contained in food, consisting 



chiefly of phosphate of lime and magnesia, present the 

 animal with the materials of which the bony skeleton 

 of its body principally consists. They may be called, 

 therefore, bone materials. 



2. The saline substances chlorides of sodium and potas- 



sium, sulphate and phosphate of potash and soda, and 

 some other mineral matters occurring in food supply 

 the blood, juice of flesh, and various animal juices with 

 the necessary mineral constituents. 



3. Albumen, gluten, legumin, and other nitrogen-containing 



principles of food, furnish the animal with the materials 

 required for the formation of blood and flesh ; they are 

 called, therefore, flesh-forming substances. 



4. Fats and oily matters of the food are employed to lay on 



fat, or to support respiration and animal heat. 



5. Starch, sugar, gum, and a few other non-nitrogenized 



substances, consisting of carbon, hydrogen, and oxygen, 

 are used to support respiration (hence they are called 

 elements of respiration), or they produce fat when given 

 in excess. 



6. Starch, sugar, and the other elements of respiration alone 



cannot sustain the animal body. 



7. Albumen, gluten, or any other albuminous matter alone 



does not support the life of herbivorous animals. 



8. Animals fed upon food, deficient in earthy phosphates 



or bone-producing principles, grow sickly and remain 

 weak in the bone. 



9. The healthy state of an animal can only be preserved by 



a mixed food which contains flesh-forming constituents 

 as well as heat-giving principles, and earthy and saline 

 mineral substances in proportion, determined by ex- 

 perience and adapted to the different kinds of animals, 

 or the particular purpose for which they are kept. 



Having explained the different purposes to which the proxi- 

 mate constituents of food are applied in the animal economy, I 



