THE FOOD AND DIGESTION 321 



I. Cereals. From the seeds of these, meals and flours are 

 prepared. 



Oatmeal contains about 15 per cent, of proteids, about 

 6 per cent, of fats, and about 65 per cent, of carbohydrates. 



Wheaten flour contains about 10 per cent, of proteid, 1 per 

 cent, of fat, and 75 per cent, of carbohydrates. 



Ordinary white bread, prepared from wheaten flour, con- 

 tains only about 7 per cent, of proteids and 55 per cent, of 

 carbohydrates. 



The proteids of these cereals are mixtures of various 

 albumins and globulins which do not differ in their char- 

 acters from the animal proteids. They are most abundant 

 in the outer part of the grain, just under the capsule. 



While oatmeal and maize contain a fair proportion of fat, 

 the other cereals are poor in this constituent. 



The chief constituents of all these seeds are the carbo- 

 hydrates stored as starch. 



II. Legumens. The seeds of the leguminosse peas, beans, 

 and lentils are valuable constituents of the diet, being speci- 

 ally rich in proteids. In the dry state they contain some- 

 thing over 20 per cent, of proteid and about 50 per cent, of 

 carbohydrates. 



The proteids are a mixture of albumin and globulin, which 

 have been classified together as legumin. 



The fats are small in amount, and the carbohydrates, 

 though abundant, are less so than in the cereals. 



III. Bulbous Plants. The underground stems of certain 

 plants develop tuberous growths in which material for the 

 nourishment of the plant is stored. These plants belong to 

 different natural orders, but they may here be classified to- 

 gether. The most commonly employed are potatoes, turnips, 

 and carrots. The amount of proteid is small, something 

 under 2 per cent., while the carbohydrates in the potato reach 

 20 per cent., but in other tubers only about '10 per cent. 



Such tubers are chiefly valuable as a source of carbo- 

 hydrates though they also contain a small proportion of 

 proteids. 



IY. Green Vegetables. Cabbage, cauliflower, spinach, 

 lettuce, &c., are useful additions to the diet, but their 

 value as a source of the proximate principle of the 



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