The physiology of digestion, considered with relation to the principles of dietetics / By Andrew Combe.

  • Combe, Andrew, 1797-1847.
Date:
1845
Catalogue details

Licence: Public Domain Mark

Credit: The physiology of digestion, considered with relation to the principles of dietetics / By Andrew Combe. Source: Wellcome Collection.

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    GENERAL REMARKS ON WASTE, GROWTH, AND NUTRITION. Waste or loss of substance always attendant on ac- tion—In the vegetable and animal kingdoms waste is greater than in the physical—Living bodies are distinguished by possessing the power of repairing waste—Vegetables, being roeted in one place, are always in connection with their food—Animals, being obliged to wander, receive their food at intervals into astomach—Nutrition most active when growth and waste are greatest —In vegetables the same causes which increase these processes also stimulate nutrition—But ani- mals require a monitor to warn them when food is needed—The sense of Appetite answers this purpose—The possession of a stomach implies a sense of Appetite to regulate the supplies of food. AMONG the properties by which liv- ing bodies are characterised, there are perhaps none more remarkable than those which have reference to the re- ception and assimilation of their food. Without continually receiving supplies of nourishment, and without a power of assimilating (from similis like—making tnto like) or converting that nourish- ment into their own living structure, neither animals nor vegetables could continue to exist. In all animals, ac- cordingly, however rudimentary their form, and even where no trace of brain, heart, lungs, spinal marrow, or other distinct organization, can be discovered, some provision for the reception and assimilation of food is uniformly to be met with. In the lowest of all, indeed, the entire being seems to be little else than an apparatus for nutrition. The reason of this never-failing pro- vision is not difficult to be discovered. At every instant of time a change in the cdnstituent elements of the animal body is going on. Every movement and every vital act are accompanied by @ corresponding change in the organs by which they are performed. After having served its appointed purpose, the old material separates from the minion of purely chemical laws, and is excreted or thrown out from the body in the form of new compounds, the con- tinued presence of which in the system would prove hurtful, and even destruc- tive to life. In whatever act we may be engaged, even in the very act of breathing, organic change and organic waste are invariable concomitants, and the greater the activity, the more rapid the change and waste; and, conse- quently, the greater the need of fresh supplies of nourishment to replace the loss. Of these facts, we have familiar examples, both in the rapid wasting away of the body under severe muscu- lar exertion, especially when food is not supplied in sufficient quantity ; and in the very small waste which goes on when animal life is at its lowest ebb, as during the sleep of hybernating ani- mals. Constituted as we are, indeed, it is as impossible for animal activity to go on without a corresponding organic waste, as it is for any form of combus- tion to go on without a proportional consumption of fuel. Such, then, being the unalterable law of animal life, it is plain, that, without a corresponding and conti- nually recurring supply of nourishment to replace the waste consequent on ac- tivity, and without the existence of a power of assimilating that nourish- ment, decay and death would speedily ensue. But it is not merely as repla- cing waste materials that fresh sup- plies are required. Liebig, in his late interesting researches into animal che- mistry, has advanced strong grounds for believing that no small portion of the food we consume is requisite more for the purposes of respiration than of direct nutrition, and that its chief ob-