The physiology of digestion, considered with relation to the principles of dietetics / By Andrew Combe.
- Andrew Combe
- Date:
- 1845
Licence: Public Domain Mark
Credit: The physiology of digestion, considered with relation to the principles of dietetics / By Andrew Combe. Source: Wellcome Collection.
40/188 page 18
![weight, but we speedily perceive the error when we recollect that, in the horse and the cow for example, the mouth is on a level with the ground when feeding, or drinking, and that the morsel or water is consequently propelled upwards into the stomach against its own gravity. It is well known, also, and often made a matter of public exhibition, that a man can swallow even liquids when standing on the crown of his head, with the natural position of the stomach re- versed. Deglutition is easier and quicker when the appetite is keen, and the ali- mentary bolus or morsel is moist and properly softened. It is low and dif- ficult when the morsel is dry and mealy, and the appetite nauseated. In vomit- ing, the action of the muscular fibres is inverted, or proceeds from the lower end of the gullet towards the mouth; and hence the object is carried up- wards, instead of downwards as in the natural order. CHAPTER IV. ORGANS OF DIGESTION—THE STO- MACH—AND ITS STRUCTURE. Surprising power of digestion—Variety of sources of food—All structures, however different, formed from the same blood—General view of digestion, chymificetion, chylification, sanguification, nu- trition—The stomach in polypes, in quadrupeds, and in man—Its position, size, and complexity in different animals—Its structure; its peritoneal, muscular, and villous coats; and uses of each— Its nerves and bloodvessels, their nature, origins, and uses—The former the medium of communi- cation between the brain and stomach—Their re- lation to undigested food—A nimals not conscious of what goes on in the stomach—Ad vantages of this arrangement. Ir, in the whole anima] economy, where all is admirable, there be one operation which, on reflection, appears more wonderful than another, and which evinces, in a higher degree, the prodigious resources and power of the Creator in fashioning every thing to His own will, it is perhaps that by which the same kind of nutriment is extracted from apparently the most op- posite varieties of food consumed by living beings. t Remarkable, however, as this uni- formity of result undoubtedly is, it be- comes still more striking when we con- template the variety of sources from which food is derived for the support of animal life. To use the words ofa late popular writer, “ There is no part of the organized structure of an ani- mal or vegetable, however dense its texture or acrid its qualities, that may not, under certain circumstances, be- come the food of some species of in- sect, or contribute in some mode to the support of animal life. The more suc- culent parts of plants, such as the leaves or softer stems, are the prin- cipal sources of nourishment to the greater number of larger quadrupeds, to multitudes of insects, as well as to numerous tribesof otheranimals. Some plants are more particularly assigned as the appropriate nutriment of parti- cular species, which would perish if these ceased to grow: thus the silk- worm subsists almost exclusively upon the leaves of the mulberry-tree ; and many species of caterpillars are at- tachedeach to a particular plant, which they prefer to all others. There are at least fifty different species of in- sects that feed upon the common net- tle; and plants of which the juices are most acrid and poisonous to the generality of animals, such as euphor- bium, henbane, and nightshade, af- ford a wholesome and delicious food to others.”* Nor are the precision and accuracy with which the same fluid—the blood—affords to every structure of the body the precise spe- cies of nourishment or secretion which its elementary composition requires, less admirable and extraordinary than its own original formation from such a variety of materials. To bone, the blood furnishes the elements of bone with unerriug accuracy; to muscle the same blood furnishes the elements of muscle,—to nerves the elements of nerve,—to skin the elements of skin, —and to vessels the elements of ves-. sels ;—and yet, while each of these dif- fers somewhat in composition from the others, the constituent elements of the * See Roget's Bridgewater Treatise, vol. li. p. 59.](https://iiif.wellcomecollection.org/image/b33284921_0040.jp2/full/800%2C/0/default.jpg)
