Elements of the theory and practice of cookery

1 Roots of certain plants sometimes bud and sprout. Scoop out a carrot or a sweet potato for half its length ; hang up this carrot or sweet-potato cup by a string, and keep it full of water. Sprouts will appear, but not from regularly placed eyes or bud-scales, as on pota- toes or other plant-stems. ACID AND SALT SUPPLYING FOODS 237 381. How plants and animals make food ready for man. — Roots are the feeding organs of plants. They suck up water and food from the earth. We have seen that cattle turn grass into beef and milk for our use ; grass, grain, and every edible plant that grows, work the mineral matter of the earth into cellulose, starch, sugar, for animals or men. 382. Analysis of Peas. — A. Rub some cooked green or dried peas through a sieve, washing the pulp through with water. What is left on the sieve ? B. Test for starch the pulp that passes through. C. Analyze beans in the same way. 383. Vegetables that supply proteid : peas, beans, lentils. — We see that peas and beans may be considered starchy vegetables. But they also contain much pro- teid matter, as is proven by their turning yellow if treated with nitric acid. In China a kind of cheese is made from them. This fact makes the name " vege- table casein," sometimes given to one of the proteids in peas and beans, seem appropriate. Legumin is, how- ever, a better name for this substance. Although there are greater quantities of other proteids in peas and beans," they, together with lentils, another of the pulses, or pod-forming plants, are classed as legumes. Studies of Growing Vegetables 384. — 1. Make drawings of a pea-plant or a bean-plant at dif- ferent stages of growth, noting how the cotyledons shrivel as the seedling grows. Explain this. (§§ 146 and 147.) 2. A. — Cover half an onion split lengthwise, with warm water, renewing this several times a day to hasten the experiment. 238 THEORY AND PRACTICE OF COOKERY What takes place in the centre of the onion, and at the base of the leaves? What becomes of the leaves as the shoot grows? Where does the onion store its food ? B. Test the onion for starch. An onion is a bulb, that is, an underground stem sur- rounded by overlapping leaves, thickened by stored-up food material. 385. Food value of vegetables ; selecting vegetables with regard to food to be served at the same meal. — All vege- tables are valuable for their mineral salts, some furnish a considerable amount of carbohydrates, a few are rich in both carbohydrates and proteids. All, however, con- tain a large proportion of water and comparatively indigestible material. This makes them suitable to eat with concentrated foods, such as eggs and meat ; for this indigestible stuff, consisting largely of cellulose, helps to fill the stomach and keep the mass of food loose, so that as this turns, every part of it comes in contact with the gastric juice. The rough bits of cellu- lose are useful, besides, in stimulating the intestines to action, so that their contents are kept constantly moving.