The most important members of this class of foods are the cereal grains—wheat, rye, corn, rice, buckwheat, oats, and barley. The universality of its consumption and its nutritive value place wheat-bread in the first position as an article of diet. The composition of wheat-flour is as follows :

Water......................................................  140

Fatty matters........... ....................................    1·2

Gluten......................................................  12·8

Albumen...................................................    1·8

Dextrin, sugar...............................................    7·2

Starch......................................................  59·7

Cellulose....................................................    1·7

Salts (potash, soda, lime, magnesia, phosphoric acid, etc.)...........    1·6

In the preparation of wheat-flour, the bran is separated. Important constituents of the wheat are thus removed, as the following analysis of the bran shows :

Water.....................................................  103

Fatty matters...............................................    282

Gluten....................................................   10·84

Albumen....... ...........................................    1·64

Dextrin, sugar...............................................    5·8

Starch.....................................................   22·62

Cellulose...............................................  43·98

Salts......................................................    2·52

The internal envelope of the wheat-grain contains also a ferment, know as cerealin, which has very active properties. As the proportion of bran to flour is as sixteen to eighty, it is obvious that considerable loss accrues in the preparation of superfine flour. Wheat-bread made from superfine flour is easy of digestion, owing to its lightness and sponginess permitting a rapid diffusion of the gastric juices through every part of it. Most of it is also available for nutrition; there is little residuum; hence the constipation which attends its use in large proportion relatively to the other constituents of the diet. When flour is unbolted (bran not separated), an increase of nutritive value is obtained, at the expense, however, of digestibility. A large part of the bran, probably, resists the action of the gastric juice, and hence, irritating the mucous membrane, increases by reflex action the secretions and peristaltic movements.

Whole wheat-grains, under the name of "cracked wheat" is frequently prescribed as an article of diet for invalids. It is boiled until the envelope of the grain is burst open, and is eaten with cream and sugar. Obviously such a combination forms a food of great excellence. The special advantage which it possesses, besides its nutritive value, is its laxative action.

Ordinarily, wheat-bread made of superfine flour is to be preferred for the use of invalids. To obviate the constipating action of such bread, and to obtain a laxative effect, various expedients are adopted. Bran, rye, and corn meal, and, in some kinds of bread, molasses, are added to the dough, forming those varieties known as Graham bread, brown bread, and Boston brown bread.

The important quality of lightness is imparted to wheat-bread by thorough incorporation of carbonic-acid gas with the dough. Two processes are employed for this purpose: By the addition of yeastr fermentation takes place at the expense of a portion of the starch, and carbonic acid and alcohol are produced. By mechanical means, carbonic acid obtained from other sources is mixed with the flour. The latter is known as "aerated bread." Obviously, the mechanical process is more economical because there is no loss of flour. It furnishes usually a lighter and drier bread, and is more easily digested. Bread made by the fermentation process is not unfrequently moist and heavy, and sour, because the fermentation has proceeded beyond the alcoholic stage. "French bread" is lighter, drier, and better baked, than ordinary baker's fermented bread. Warm, fresh bread is not suitable for invalids. It can not be so perfectly masticated as older bread, and, not reaching the stomach in a state to permit diffusion through the mass of the gastric juices, lies unchanged for hours.

According to Smith, the ultimate composition of wheat-bread is as follows:

Water......................................................  37·0

Starch......................................................  47·4

Sugar.......................................................    3·6

Fat........................................................    1·6

Salts........................................................    23

Macaroni stewed in milk is sometimes prescribed for the sick. Prepared with butter, cheese, and condiments, it is not an appropriate food for invalids. In composition it consists chiefly of gluten, and of course starch—but in less proportion than in bread—and of fat. The cylindrical tubes in which it occurs are formed by passing the paste of flour (gluten) through perforated plates.

Bread requires from three and a half to four hours for complete digestion. Brown bread digests somewhat more slowly.

Barley is but rarely used as food in this country. It is occasionally prescribed for the sick in the form of infusion—a demulcent drink— and is frequently added to soup. It has the following composition (Smith):

Water......................................................  150

Starch......................................................  69·4

Sugar......................................................    4·9

Fat.........................................................    2 4

Salts........................................................    20

Albuminous substances........................................    6·3

Rice is one of the most digestible of vegetable foods, requiring, when boiled, about one hour. Its nutritive value is not equal to wheat, because it consists chiefly of starch. The following is its proximate constitution:

Water..................................................... 13·0

Nitrogenous matter........................................... 6·3

Starch...................................................... 79·1

Sugar....................................................... 0·4

Fat........................................................ 0·7

Salts........................................................ 0·5

Rice-water, or decoction of rice, like the corresponding preparation of barley, is used as a demulcent drink in fevers and intestinal disorders. Boiled rice is frequently prescribed as a diet for invalids with weak digestion, and is enriched by the addition of milk and cream, and eggs (rice-pudding).