Animal physiology / by John G. M'Kendrick.

  • John Gray McKendrick
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Animal physiology / by John G. M'Kendrick. Source: Wellcome Collection.

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    from without. This group contributes chiefly to the fatty tissue of the body. The gelatinous group is represented by cow-heel, isinglass, and such-like substances, yielding jellies and soups that stiffen on cooling; while the saline group includes mineral matters, especially common salt, and phosphates of the alkalies, and of lime, &c. The saline or mineral matters form bone, tooth, &c., and they are found in variable proportions in almost every fluid and solid in the body. It must be remembered, however, that a mix- ture of all of these constituents of food is essential to the formation of a nutritious diet, and, moreover, that there must always be a certain amount of sapidity or flavour in the food. We should turn with disgust from a mess con- sisting of these constituents, even in proper proportions, if it were not properly cooked. The best example of a natural food is milk. It contains water, albumen in the form of casein or cheese, fat in the form of butter, sugar, and various salts. Hence it is nature's food for all young animals of the mammalian group. 75. Conditions determining the qttantity of Food,—These are: (i) the amount of oxygen in the atmosphere and the temperature ; (2) the amount of mental and bodily exertion ; and (3) the activity of growth. Exercise and exposure to cold sharpen the appetite, and thus lead to more food being taken. It is also well known that dwellers in the arctic regions not only eat a great deal of food, but of that kind which, by oxidation by the oxygen of the air, is heat-pro- ducing—namely, oleaginous matter. On the other hand, the inhabitants of the tropics eat sparingly, and chiefly of products rich in carbo-hydrates (that is, substances com- posed of carbon, hydrogen, and oxygen, with enough of the latter to oxidise the two former), such as starch, sugar, &c. In a temperate clime, something between the two extremes is found to be most conducive to health. 76. Food and Work,—It is evident that the amount of food must have some direct relation to the work done by the individual. Hard work means expenditure of matter and energy, and these must be supplied by food. The fol- lowing table shews the quantities, in ounces avoirdupois, of
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