Plain well-cooked animal food, not too recently killed, and eaten in moderate quantity with bread, rice, or roasted potatoes, forms one of the most easily digested meals which can be devised for a weak stomach. Sometimes, however, potato induces acidity and flatulence, and ought not to be used. Venison and most kinds of game are very suitable in the same circumstances.
In some conditions of the system, where the condition is irritable and the mode of life not sufficiently active, red highly animalized meat proves too stimulating, although easy of digestion. The same thing happens during recovery from illness; and hence fish, chicken, and other white meats, which excite less and are digested more slowly, are often allowable where beef, mutton, pork, &c. cannot be taken with impunity. For the same reason, white and young meats are the best adapted for the excitable systems of the young.
It would be easy to fill many pages with disquisitions about the preference due to individual articles of food, were such the purpose which I had in view. But books devoted to this branch of the subject abound, and are already in general circulation; and as I have nothing new to add to what is contained in them and to the general view given in a preceding chapter, it would be making a needless demand on the patience of the reader merely to repeat what is to be found in so many other works. My object is the exposition of PRACTICAL PRINCIPLES rather than of minute details; and my great aim is to enable every intelligent person to understand, not only what digestion, is, but the laws by which it is regulated, so that he may know at once WHY it is for his advantage to adhere to one course of conduct in preference to another in regard to it—WHY, in different situations, diet requires to be modified in order to adapt it more effectually to the varying wants of the system—and, lastly, the circumstances or rules by which such modifications ought to be determined. If I have succeeded in the attempt to explain any of all of these principles sufficiently to render them susceptible of a practical application by the reader, not only I will be greatly pleased, but the advantage to him will speedily convince him that I have acted judiciously in forsaking the beaten path, and drawing his attention to truths of still greater importance to his welfare than those which are most commonly treated of under the title of Dietetics.
CHAPTER IV.
CONDITIONS TO BE OBSERVED BEFORE AND AFTER EATING.
General laws of organic activity apply to the stomach as well as to other parts—Increased flow of blood towards the stomach during digestion—Hence less circulating in other organs—And consequently less aptitude for exertion in them—Bodily rest and mental tranquillity essential to sound digestion—Rest always attended to before feeding horses—Hence also a natural aversion to exertion immediately after eating—Mischief done by hurrying away to business after meals—Severe thinking hurtful at that time—Playful cheerfulness after dinner conducive to digestion—The mind often the cause of indigestion—Its mode of operation explained—Also influences nutrition—Illustration from Shakspeare.—Importance of attending to this condition of health enforced.
Having now discussed the principles by which the number, quantity, and quality of our meals ought to be regulated, we have next to consider the conditions required for the healthy performance of digestion after the aliment has reached the stomach, and to deduce from them such practical rules as shall tend to facilitate the accomplishment of the process.
Among the circumstances which favour digestion, the observance of bodily rest and mental tranquillity for some time before and after every meal, is perhaps the most important; its influence depends on a well-known law of the animal economy, already frequently alluded to, but to which, that it may be fully understood, I must again shortly refer.
Whenever any living part is called into vivid action, an increased flow of blood and of nervous energy towards it immediately commences, to enable it to sustain the requisite degree of excitement, and continues till some time after the activity has ceased. In accordance with this law, whenever food is swallowed, the lining membrane of the stomach becomes suffused with blood, and, owing to the greater distention of its vessels, its colour changes from a pale pink to a deep red hue. After digestion is completed, and the unusual supply of blood is no longer required, the vessels again diminish, and the colour returns to its original tint. In St Martin’s stomach, these changes were so often seen by Dr Beaumont, as to render their occurrence as fully demonstrated as any circumstance with which we are acquainted. Even had they never been seen, the simple examination of the structure of the stomach would lead us directly to the inference that it receives an additional supply of blood when engaged in digestion; for the very act of its distention by food renders the course of its bloodvessels less tortuous, and the flow of blood through them consequently more easy and rapid. In the case of the stomach, indeed, the increased circulation is doubly required; not only as in other parts to enable it to act with greater vigour, but also to supply the very copious secretion of gastric and mucous fluids necessary for digestion, and which we have seen to commence the moment food touches the mucous coat. The quantity of gastric juice actually secreted at each meal cannot easily be determined; but as more than an equal weight of it is required for the solution of food out of the stomach, its amount must be very considerable. Indeed we know that, on one occasion, when St Martin dined on broiled mutton and bread without any liquids, the gastric secretion was so copious, that half an hour afterwards the “stomach was as full of fluids as when he drank a pint immediately after eating;”[55] and, as the whole of this must have been derived directly from the blood circulating through the vessels of the stomach, they must necessarily have received a very large supply to enable them to furnish it.
It is obvious, however, that the great afflux of blood which takes place towards the stomach and intestines during digestion, cannot occur without a corresponding diminution in the quantity circulating on the surface and in other distant parts of the body, attended of course with a diminished power of action in them. Hence, for some time after a full meal, there is an inaptitude for vigorous thinking and bodily exertion, a depression of respiration, and, in delicate persons, a degree of coldness or chill felt over the whole body. But, under ordinary circumstances, this depression is not of long continuance. After the requisite secretions have been provided for the solution of the food and the formation of the chyle, a reaction and change in the distribution of the blood, now partially renewed by the admixture of nutritive chyle, ensue, and, by the stimulus which they afford, soon fit the person for the active resumption of his ordinary duties.