AND AGRICULTURE. 81 



varieties which are deficient in that substance, 

 It is because of the fatty matter contained in 

 oil-cake, that it is so efficient in improving the 

 condition of stock to which it is fed. 



Phosphate of lime, and other saline or inor- 

 ganic substances, must also be contained in the 

 food of animals, to supply the constant waste of 

 the osseous system (the bones), the salts in the 

 blood, etc. 



The gluten and saline matter also serve an- 

 other purpose besides supplying the constant 

 waste of the system; they daily add to the 

 weight of the body of the animal. Hence you 

 see why it is that a growing animal requires 

 much more of these kinds of food than one 

 which has attained his growth. The full-grown 

 animal has only its daily waste to make good ; 

 but the growing animal has also an additional 

 amount of new substance to make daily, besides 

 that quantity needed to supply the daily waste 

 of its system ; if it did not do this, it could 

 never become larger, or increase in weight. 



Questions. Why should the food of animals contain 

 phosphate of lime, and other inorganic substances ? What 

 other purpose does gluten and saline substances subserve ? 

 Why does a growing animal require more of those substances 

 than a full-grown one ? 



