330 HANDBOOK OF PHYSIOLOGY. 



vegetables. It is derived in all cases, so it is supposed, by organic 

 compounds, into which it is built up during plant life, or during the life 

 of other animals (haBmatogens). 



Liquid Foods. 



Water is consumed alone, or together with certain other substances 

 used to flavor it, e.g., tea, coffee, etc. Tea in moderation is a stimulant, 

 and contains an aromatic oil to which it owes its peculiar aroma, an 

 astringent of the nature of tannin, and an alkaloid, tlieine. The composi- 

 tion of coffee is very nearly similar to that of tea. Cocoa, in addition 

 to similar substances contained in tea and coffee, contains fat, albumin- 

 ous matter and starch, and must be looked upon more as a food. 



Beer, in various forms, is an infusion of malt (barley which has 

 sprouted, and in which its starch is converted in great part into sugar), 

 boiled with hops and allowed to ferment. Beer contains from 1.2 to 8.8 

 per cent of alcohol. 



Cider and Perry, the fermented juice of the apple and pear. 



Wine, the fermented juice of the grape, contains from 6 or 7 (Rhine 

 wines, and white and red Bordeaux) to 24-25 (ports and sherries) per 

 cent of alcohol. 



Spirits, obtained from the distillation of fermented liquors. They 

 contain upward of 40-70 per cent of absolute alcohol. 



The effect of cooking. In general terms this may be said to make 

 the food more easily digestible; this usually implies two alterations, 

 food is made more agreeable to the palate and also more pleasing to the 

 eye. Cooking consists in exposing the food to various degrees of heat, 

 either to the direct heat of the fire, as in roasting, or to the indirect 

 heat of the fire, as in broiling, baking, or frying, or to hot water, as in 

 boiling or stewing. The effect of heat upon (a) flesh is to coagulate the 

 albumin and coloring matter, to solidify fibrin, and to gelatinize ten- 

 dons and fibrous connective tissue. Previous beating or bruising (as 

 with steaks and chops) or keeping (as in the case of game), renders the 

 meat more tender. Prolonged exposure to heat also develops on the sur- 

 face certain empyreumatic bodies, which are agreeable both to the taste 

 and smell. By placing meat in hot water, the external coating of albu- 

 min is coagulated, and very little, if any, of the constituents of the 

 meat are lost afterward if boiling be prolonged; but if the constituents 

 of the meat are to be extracted, it should be exposed to prolonged sim- 

 mering at a much lower temperature, and the "broth" will then contain 

 the gelatin and extractive matters of the meat, as well as a certain 

 amount of albumin. The addition of salt will help to extract myosin. 



The effect of boiling (b) an egg is to coagulate the albumen, which 

 helps to render it more easily digestible. Upon (c) milk, the effect of 



