[397] SCIENTIFIC MANUAL. Ill 



From the albuminoids of their food, animals derive the 

 flesh and muscle of their bodies ; from the carbo-hydrates, 

 they derive heat and fat ; from the mineral elements of 

 their food, the saline matters of the blood, and the phos- 

 phate of lime of their bones are derived. 



As in plants, a suitable combination of all these ele- 

 ments which contribute to animal nutrition, is necessary 

 to produce a normal development. The ratio in which the 

 constituents of food must exist, depends upon climate, 

 the age and condition of the animals fed, and the purposes 

 for which they are fed. 



Nature supplies, in character and variety, the food best 

 suited for man and beasts, in the different zones of the 

 earth. In the frigid zone, an excess of carbon is needed 

 to supply the loss of animal heat consequent upon very 

 low temperature. This is supplied to man in the oils and 

 fat of the lower animals in that region, which ' accumulate 

 vast quantities of these substances in their bodies. The 

 circumstances of climate demand a liberal consumption of 

 carbo-hydrates to supply the rapid combustion necessary 

 to the preservation of animal heat ; and forbid the ex- 

 ertion which, in more temperate climates, causes a waste 

 of muscular tissue. 



In the torrid zone, on the contrary, the minimum quan- 

 tity of the carbo-hydrates is required, since but little car- 

 bon is needed to keep up the normal animal heat, while 

 only a small consumption of albuminoids is necessary to 

 supply the waste of muscular tissue incident to the climate. 

 Instead of oils and fats, the denizens of the torrid zone 

 subsist largely upon cooling food, such as fruits and vege- 

 tables, which abound in profusion throughout the year. 



In temperate zones, where we find the greatest physical 

 and menfal activity, nature also supplies food in the neces- 

 sary variety, and of the proper kind to meet the wants of 

 both man and beast. Here we*find the vegetable products 

 of the most solid and nutritious character, having an equi- 



