CHAPTER X 



THE FOOD OF ANIMALS 



THE term food includes all substances which con- 

 tribute to nutrition and furnish energy, whether they 

 simply assist in the process, or are actually appropriated, 

 and become tissue. With the food is usually combined 

 more or less indigestible matter, which is separated in 

 digestion. 



Food is derived from the mineral, vegetable, and ani- 

 mal kingdoms. Water and salt, for example, are inor- 

 ganic. The former is the most abundant, and a very 

 essential article of food. Most of the lower forms of 

 aquatic life seem to live by drinking : their real nourish- 

 ment, however, is present in the water in the form of 

 fine particles. The earthworm, some beetles, and cer- 

 tain savage tribes of men swallow earth ; but this, like- 

 wise, is for the organic matter which the earth contains. 

 As no animal is produced immediately from inorganic 

 matter, so no animal can be sustained by it. 



Nutritious or tissue-forming food comes from the 

 organic world, and is albuminous, as the lean meat of 

 animals and the gluten of wheat ; oleaginous, as animal 

 fat and vegetable oil ; or saccharine, as starch and sugar. 

 The first is the essential food stuff ; no substance can 

 serve permanently for food that is, can permanently 

 prevent loss of weight in the body unless it contains 

 albuminous matter. As stated before, all the living 

 tissues are albuminous, and therefore albuminous food 

 is required to supply their waste. Albumen contains 



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