The time ordinarily occupied in the process of chymification, when the food has been properly masticated, has been found to be four or five hours; the three first hours of the period, is occupied in the process of intermixing the food, after it enters the stomach, with the gastric juice. After this is accomplished, an alternation of contraction and expansion of the stomach, or a kind of churning motion takes place, and continues until the whole mass is converted into chyme, and conveyed to the first intestines, or duodenum, to undergo another change.
CHYLIFACTION.
Chylifaction, or the formation of chyle, is the next great step in the process of digestion. This takes place in the duodenum; the chyme from the stomach is let into the intestines little by little; a valve at the lower opening, or outlet of the stomach prevents it from passing any faster than it can be disposed of, in the formation of chyle. This fluid is a thin, milky liquid, extracted from the chyme, and then taken up by absorbent vessels, called lacteals; the chyme passes slowly through the duodenum, and, in doing so, becomes mixed with another fluid furnished from the pancreas, or sweetbread, and the bile from the liver; passing slowly through this large intestine, ample time is given for the lacteal to take up all that is valuable, to be carried into the circulation, for the nourishment and support of the system. This chyle, taken up by the lacteals, is directly converted into blood, and, in many of its characteristics, it very closely resembles blood. The process by which this conversion is carried on, is called absorption; that class of absorbent vessels called lacteals, are not only found in the first intestine, or duodenum, but are distributed along the small intestines, for the purpose, as before stated, of conducting the chyle in its appropriate course, for the formation of blood.
EVACUATION.
Evacuation, or the discharge of the refuse part of the food, through the bowels, is another and the last step in the process of digestion. This part of the subject has a very important bearing on the condition of the health; it is impossible for any one to possess good health, while this office of the bowels is imperfectly performed. If the bowels are relaxed and irritable, the food is borne along too soon and too rapidly; this causes the process of chylification to be imperfect—the chyle is imperfectly formed, and the lacteals have not sufficient time to absorb it from the mass; this prevents the food from nourishing the system. Hence, those who suffer from chronic diarrhœa may eat largely, and yet grow weaker and weaker; their food does not nourish them; the nutritious part passes off through the bowels, instead of being taken into the blood. If the bowels, on the other hand, are constipated, the consequences are no less unhappy. No one can possibly be well with costive bowels; the free and easy action of the bowels is as truly essential to health, as the free circulation of the blood. When the bowels are sluggish, the process of absorption of the chyle is retarded; and what is absorbed, is less pure and healthy, so the quality of the blood is impaired.
Besides the evils already mentioned, a costive state of the bowels often causes a pressure of blood on the brain, and also derangement of the nervous system, excitability of the nerves, nervous headache, depression of spirits, and a long catalogue of sufferings, too numerous for details. Habitual costiveness impairs the tone of the stomach, and prevents its healthy action; piles, also, with various degrees of severity, are often caused, directly or indirectly, by constipated bowels.
The causes of constipation are various, and to point them out in detail would be, perhaps, a fruitless task. But there is one cause, and a very common one, which claims attention here; it is the habit of inattention to, and neglect of, the natural promptings of the bowels to evacuate themselves. Thousands on thousands, especially females, by a habit of checking the natural inclination of the bowels to throw off their contents, have brought upon themselves habitual costiveness, which, in time, has cost them immense suffering and wretchedness. No one should ever hold his bowels in check, if it be possible to avoid it; it can readily be perceived, that doing this would tend to diminish the natural effort of the bowels, and to collect their contents into a solid mass; then, the exertion required to empty the bowels, or the physic taken to aid or make effectual that exertion, tends also to increase the difficulty.
A habit of costiveness should always be removed, if possible; and the best way of doing this, is by a course of discipline. Those articles of food should be selected, which have an influence to keep the bowels open. Bread, made of flour, has a tendency to constipate them; but brown bread, and bread made of wheat meal, have a tendency to open them—also molasses, taken with food, has an additional tendency; fruits and greens, if the stomach can bear them, are adapted to relieve costiveness. The influence of the mind should also be brought to bear upon this difficulty; the operation of the mind on the physical system is very great, especially in chronic complaints.
A person with costive bowels, should have a mental determination to have a natural evacuation of the bowels, at some regular hour in the morning—just after breakfast should be preferred. By a mental calculation, by bearing the subject in mind, by thinking and desiring, by intending to have the bowels move about that hour, very much may be done by way of facilitating such a result. But if, instead of attending to a favorable diet, and of thinking on the subject at the proper time, we treat the difficulty with medicines alone, we do harm rather than good: for the more alteratives we take, the more we increase the trouble; the physic only overcomes the constipation for the time, and afterward leaves the bowels in a more torpid state. Still, rather than endure the consequences of costiveness, it is better to take alteratives, in conjunction with other means, until the difficulty can be removed. When alteratives are used in conjunction with discipline, they should be of the mildest kind. No proper pains should be spared, in overcoming this derangement of nature, till a habitual movement of the bowels once in twenty-four hours, is secured.—Coles, on Health.