Observations on certain parts of the animal oeconomy : inclusive of several papers from the Philosophical transactions, etc. / by John Hunter ... ; with notes by Richard Owen.
- John Hunter
- Date:
- 1840
Licence: Public Domain Mark
Credit: Observations on certain parts of the animal oeconomy : inclusive of several papers from the Philosophical transactions, etc. / by John Hunter ... ; with notes by Richard Owen. Source: Wellcome Collection.
Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)
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![tion than an egg hard boiled, although the raw one must be coagu- lated in the stomach before it can be digested; and it has likewise been observed, that what is easy of digestion is one stomach will not be so in another; but such cases may probably arise from the stomach not being in a healthy state. In many animals the whole of the food does not appear to be digested, the substance in part being found in the fasces ; for it a dog is fed with tallow, his excrements will consist of a somewhat firm unctuous substance, so that the oil is only digested in part. The circumstance of some part of the food, though digestible, not being acted upon by the gastric juice, may arise from two causes: first, from many parts of vegetables being too firm in texture to be digested in the same time with the other food, and being therefore carried along in a crude state, together with the chyle, into the duodenum; and secondly, from the stomach at the time being so much disordered as to digest imperfectly. We know that food may lie a considerable time in the stomach when it is diseased without being digested. Food has been retained in the stomach twenty-four hours, and thrown up without being in the least altered, the animal at the time not requiring nourishment: this often arises from disease, and is also the case with those which go to rest in the winter. The powers of digestion may in some instances be estimated by the appearance of the excrement, in which, if the food appears not to be much altered, we may conclude that digestion has had little or no influence on it. Thus, the excrement of a flea, that has lived on blood, is nearly, to appearance, pure blood, not having even lost its colour. Animals take food in proportion to the quantity of nourishment contained in it, of which the stomach appears, from instinct, to be capable of judging; and also in proportion to the powers they pos- sess of converting what they eat into chyle. A caterpillar, perhaps, eats more in proportion to its size than any other animal that lives on the same kind of food ; for not having the power of dissolving the vegetable, but only of extracting a juice or infusion from it, the bit of leaf comes away entire, coiled up and hardened ; but, by being put into water, unfolds like tea. There are few animals that do not eat flesh in some form or other, while there are many who do not eat vegetables at all; and therefore the difficulty to make the herbivorous eat meat is not so great as to make the carnivorous eat vegetables. Where there is an instinctive principle in an animal, directing it either to the one species of food or the other, the animal will certaintly die rather than break through of its own accord that natural law ; but it may be made to violate every natural principle bv artificial means. That the hawk tribe can be made to feed upon bread, I have known these thirty years; for to a tame kite I first gave fat, which it ate very readily; then tallow and butter; and afterwards small balls of Boiled veal was found to be two-thirds more digested than the same meat roasted &c. Muscular tissue, skin, gristle, tendons, bone, were digestible in the order here set down.]](https://iiif.wellcomecollection.org/image/b21131545_0106.jp2/full/800%2C/0/default.jpg)
