z OUR FAEM CROPS. 



rials for the building up of the material parts of the body, 

 such as the bones, flesh, skin, &c. Thus " food fuel" is being 

 constantly required for the one, and "food materials" for 

 the other. The regularity of this requirement constitutes 

 health any continued departure from it, disease. 

 < .It is generally conceded that, under ordinary conditions, 

 those conktifo&oitS'a're required in certain proportions ; con- 

 seqviefrubly scuy substance containing these classes of consti- 

 tuent *m the l*e*c[uirec[ proportions would by itself sustain 

 human life for a longer period than other substances in 

 which the relative proportions were not so suitable. These 

 constituents we are accustomed to classify under the heads 

 of 1, Non-nitrogenous, or heat -giving and fat-forming 

 compounds; and, 2, Nitrogenous, or flesh -forming and 

 plastic compounds ; and from experience, both scientific and 

 practical, we have been led to look upon the proportion of 

 six of the former to one of the latter as that which will, under 

 ordinary conditions, most satisfactorily meet the require- 

 ments of the human frame in the northern temperate zone. 

 Now, wheat happily possesses the two classes of constitu- 

 ents in these desirable proportions (see page 90), and has 

 therefore been taken as the standard by which the nutri- 

 tive value of all our other food-grains has been gauged. 



In barley, oats, and rye, the relative proportions, 

 though they vary but little, are not so suitable. If they 

 are used exclusively as substitutes for wheat they gener- 

 ally derange the bodily health of the consumer, and we 

 only find them forming the food of the people under cir- 

 cumstances where wheat cannot be procured. Beans 

 and peas show a large excess of the nitrogenous or flesh- 

 forming compounds ; while in the Indian corn and the rice 

 of the hotter and tropical climates, the non-nitrogenous 

 constituents form a large proportion of their whole sub- 

 stance. These latter food-grains, therefore, would require 

 to be usually accompanied by some additional substances 



