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an unmixed gain. The teeth require exercise as well as other parts of the body, and if the cook or the knife and fork do their work for them, we find that they lose their health, and decay. Artificial substitutes for those things which nature has bestowed on us, always have an injurious tendency. Those people who sit in hot rooms with a hat or cap on, often lose their hair, but only on that part of the head which the hat covers; and so, too, people who live on soups, and the crumb of bread, and things which give their teeth no trouble at all, lose them much sooner than those who go into the other extreme, and use them as nutcrackers.
Let us now follow the food into the mouth. Here, as you know, it undergoes the process of mastication, or chewing. That is to say, it is cut, bruised, ground down, and torn up by the teeth into a pulpy
To aid in this process, there are placed in different parts of the mouth, six organs, or, as they are called, glands, whose function or work it is to prepare and pour into the mouth the liquor which philosophers call saliva, and homely folks, spittle. This liquor not only aids the teeth in their business of reducing the food to a pulpy mass, but also assists in dissolving some portions of it. Hence, food which comes into the mouth in such a form that it does not require chewing, is in danger of being passed into the stomach without being properly mixed with the saliva ; in which case the process it should undergo in the mouth is less perfectly carried out than if it had been duly treated by the teeth, instead of by the cook or the knife and fork outside the mouth. It is therefore very important that food should be well chewed in the mouth, in order that it may be thoroughly mixed with the saliva.
But there are some kinds of food, such as new bread, pudding crust, and heavy pie crust, which the teeth cannot reduce to a pulpy mass, but only knead
them into doughy lumps. Then again, there are meats which are so tough that they defy all the efforts of the teeth to divide or tear them asunder. Now the stomach cannot well deal with lumps, and the consequence is, that if the food descends into it in that form, one of two things happens : either it is not digested at all, and passes out of the body without yielding any blood, and, therefore, without contributing to its nourishment; or else it is digested by means of an excessive expenditure of gastric juice, -of which we shall have to speak presently,—and so the waste which it causes of the living substance of the body, is much greater than the quantity of nourishment which it supplies to replace it.
These considerations shew the necessity not only of thoroughly chewing our food, but also of having a due supply of saliva to moisten it. Accordingly we find that though the glands, whose function it is to manufacture this liquid, are almost always yielding some of it, yet they supply it in greater abundance whenever anything enters the mouth. But as they cannot distinguish between food and other substances, they pour forth this extra supply whether the substance which enters the mouth be nutritious or innutritious. Sailors have learnt this by experience; and when put on a short allowance of water they assuage their thirst by keeping in their mouths a bullet, which produces à flow of saliva as great, or nearly so, as would be produced by the presence of a piece of meat. And this, I think, constitutes one objection to the practice of smoking: The smoker, when he puts his pipe or cigar into his mouth, causes an extra flow of saliva to take place, which is further favoured by the warmth of the burning tobacco. The consequence is not only that a portion of the living substance of his body is consumed in the production of this saliva, and requires to be replaced; but also that as that liquid has been drawn off beforehand, it is not forthcoming in sufficient abundance when required to aid in the chewing and digestion of our food.
After passing through the mouth, the food descends into the stomach. Here it undergoes a further
process ; it is not only churned and mixed together, but it is also exposed to the action of another liquid, which is called gastric juice, and which possesses the property of more completely dissolving it and reducing it to a sort of paste which is called chyme. The gastric juice is poured into the stomach from a great number of small tubes in its inner coats at the time when the food enters it; and as this juice, like all the other juices of the body, is derived from the blood, it is necessary that there should be a larger quantity of blood circulating through the stomach when the food is being digested in it; and we find that when the food descends into the stomach, a great rush of blood towards it takes place immediately. We ought, then, to take care, as far as we can, that no demand is made for blood in other parts of the body at the same time. We should not, therefore, go into a cold room to eat our meals, because in that case the surface of the body will require an extra supply of blood to keep up its warmth, and will thus come into competition with the stomach, and prevent it from receiving as large a supply as it would otherwise obtain. For the same reason, we should abstain from reading, studying, or taking violent bodily exercise, either during meal times or immediately after. It is computed that a full fifth part of the blood circulating through the body is present in the brain. Hence we may see what a formidable rival it must be to the stomach, if it is setting up a claim for an extra supply of blood at the time when all that can be spared is required for digestive purposes.
Nothing is more necessary to good digestion than to preserve an easy comfortable frame of mind. Mirth, laughter, cheerful conversation, and every thing that is calculated to keep us in good humour with ourselves and others, are very valuable aids to digestion. And, on the other hand, anger, jealousy, ill-temper, quarrels, and anxieties, which are very hurtful at all times, are peculiarly mischievous at dinner time. I know it must unhappily be very difficult to many of you, in times like these, to - drive dull care away ; but if you want good digestion, and all the manifold blessings that attend it, you must do so. Don't mistake me.
I do not mean that you should be careless, but that you should be free from care. Do all you possibly can to provide for yourselves and your families during the dark and gloomy period that is before us; but having taken every precaution that prudence can suggest, and having left no stone unturned to better your circumstances, force your minds
from brooding on your calamities, and remember that there is great economical and sanitary, as well as religious truth, contained in the words " Take no thought for the morrow, for the morrow shall take thought for the things of itself: sufficient unto the day is the evil thereof." I hope that this excellent institute will be of great use to you in this way ; but this is a subject which has been so ably referred to by Mr. Cobden, * in words which I have no doubt are still fresh in the remembrance of many of you, that I do not feel it necessary to do more than allude to it.
It would be tedious, and so far as our immediate purpose is concerned, useless, to describe minutely the further processes which the food undergoes after quitting the stomach, in order to its conversion into blood. It may suffice to say, that it is still further
* On the occasion of his visit to Rochdale.
dissolved into a substance which is called chyle, from which the portion available and required for blood purposes is strained off through very small vessels or tubes in the coats of the bowels, and is thus conveyed into larger channels, whence it is passed on into the veins, and enters into the circulation. Still, however, even yet, it is not prepared to enter into the composition of our bodies, or to form part of their living substance. Before it can do this, it must be presented to the air, to which it must yield up a portion of a substance called carbon, which it contains, in the form of carbonic acid gas, and from which it must obtain a gas which is called oxygen. This operation is carried on in the lungs, and it is the object of breathing to effect it. breathe we take into our lungs a quantity of air, which is drawn into a number of tubes, or air vessels, which branch into every part of them. These air vessels are lined with a network, composed of an almost infinite number of exceedingly small veins, through the coats of which the gases can pass freely, without any escape of the fluid they contain. Now, if this operation be not effected, the blood, so far from being capable of conversion into the living substance of our bodies, would be absolutely poisonous to them; and so we see that whenever the air is excluded from the lungs, as in cases of drowning, strangulation, suffocation, &c., death ensues in the course of a very few minutes; and the same would be the case if we were made to breathe air which had been deprived of its oxygen, or which was already so saturated with carbonic acid
that it could receive no more. In order, therefore, that the whole of the blood may undergo this process properly, the air which is breathed through the lungs must be pure, and must contain its proper proportion of oxygen.
But in confined rooms, or places where great numbers of persons are assem