ELEMENTS OF NUTRITION. 379 



during the day were supplied with two full feeds of the 

 steamed mixture, together with a supply of green rape- 

 plant each morning and evening. 



The result was that from three hundred and twenty- 

 four quarts of old milk twenty-three quarts of cream 

 were skimmed, of which twenty-two were churned, and 

 produced five hundred and fifteen ounces of butter, 

 which shows : 



24 ounces of butter from 16 quarts of new milk. 

 22.41 " " " " each quart of cream. 



There is, doubtless, some standard of food adapted to 

 the constitution and purposes of animals, combining with 

 bulk a due proportion of elements of respiration, such 

 as sugar, starch, &c, together with those of nutrition, 

 namely, nitrogenous compounds, phosphates, and other 

 minerals; nor can we omit oil or fat-forming substances ; 

 for, however we may be disposed to leave to philosophy 

 the discussion as to whether sugar, starch, <fcc, are con- 

 vertible into fat, yet I think I shall not offend the 

 teacher of agricultural chemistry by stating that the 

 more closely the elements of food resemble those in the 

 animal and its product, the more efficacious will such 

 food be for the particular purpose for which it is used. 



Sugar, starch, &c, vary very considerably in form and 

 proportion from vegetable oils, which closely resemble 

 animal fats. 



When we consider that plants have a two-fold function 

 to perform, — namely, to serve as food for animals, and 

 also for the reproduction of the like plants, — and that, 

 after having undergone the process of digestion, they 

 retain only one half or one third of their value as ma- 

 nure, the importance of affording a due but not excess- 

 ive supply of each element of food essential to the 

 wants and purposes of the animal will be evident. If 

 we fall short, the result will be imperfect; if we supply 

 in excess, it will entail waste and loss. 



Linseed and rape-cake resemble each other very closely 

 in chemical composition ; the latter is chiefly used for 

 manure, and its price ranges usually about half that of 



