2454. At the same instant that the air rushes into the lungs, the valve, or door between the two sides of the heart-and through which the blood had previously passed-is closed and hermetically sealed, and the blood taking a new course, bounds into the lungs, now expanded with air, and which we have likened to a wetted sponge, to which they bear a not unapt affinity, air being substituted for water. It here receives the oxygen from the atmosphere, and the chyle, or white blood, from the digested food, and becomes, in an instant, arterial blood, a vital principle, from which every solid and fluid of the body is constructed. Besides the lungs, Nature has provided another respiratory organ, a sort of supplemental lung, that, as well as being a covering to the body, _in_spires air and _ex_pires moisture;—this is the cuticle, or skin; and so intimate is the connection between the skin and lungs, that whatever injures the first, is certain to affect the latter.
2455. Hence the difficulty of breathing experienced after scalds or burns on the cuticle, the cough that follows the absorption of cold or damp by the skin, the oppressed and laborious breathing experienced by children in all eruptive diseases, while the rash is coming to the surface, and the hot, dry skin that always attends congestion of the lungs, and fever.
2456. The great practical advantage derivable from this fact is, the knowledge that whatever relieves the one benefits the other. Hence, too, the great utility of hot baths in all affections of the lungs or diseases of the skin; and the reason why exposure to cold or wet is, in nearly all cases, followed by tightness of the chest, sore throat, difficulty of breathing, and cough. These symptoms are the consequence of a larger quantity of blood than is natural remaining in the lungs, and the cough is a mere effort of Nature to throw off the obstruction caused by the presence of too much blood in the organ of respiration. The hot bath, by causing a larger amount of blood to rush suddenly to the skin, has the effect of relieving the lungs of their excess of blood, and by equalizing the circulation, and promoting perspiration from the cuticle, affords immediate and direct benefit, both to the lungs and the system at large.
THE STOMACH—DIGESTION.
2457. The organs that either directly or indirectly contribute to the process of digestion are, the mouth, teeth, tongue, and gullet, the stomach, small intestines, the pancreas, the salivary glands, and the liver. Next to respiration, digestion is the chief function in the economy of life, as, without the nutritious fluid digested from the aliment, there would be nothing to supply the immense and constantly recurring waste of the system, caused by the activity with which the arteries at all periods, but especially during infancy and youth, are building up the frame and developing the body. In infancy (the period of which our present subject treats), the series of parts engaged in the process of digestion may be reduced simply to the stomach and liver, or rather its secretion,—the bile. The stomach is a thick muscular bag, connected above with the gullet, and, at its lower extremity, with the commencement of the small intestines. The duty or function of the stomach is to secrete from the arteries spread over its inner surface, a sharp acid liquid called the gastric juice; this, with a due mixture of saliva, softens, dissolves, and gradually digests the food or contents of the stomach, reducing the whole into a soft pulpy mass, which then passes into the first part of the small intestines, where it comes in contact with the bile from the gall-bladder, which immediately separates the digested food into two parts, one is a white creamy fluid called chyle, and the absolute concentration of all nourishment, which is taken up by proper vessels, and, as we have before said, carried directly to the heart, to be made blood of, and vitalized in the lungs, and thus provide for the wear and tear of the system. It must be here observed that the stomach can only digest solids, for fluids, being incapable of that process, can only be absorbed; and without the result of digestion, animal, at least human life, could not exist. Now, as Nature has ordained that infantine life shall be supported on liquid aliment, and as, without a digestion the body would perish, some provision was necessary to meet this difficulty, and that provision was found in the nature of the liquid itself, or in other words, THE MILK. The process of making cheese, or fresh curds and whey, is familiar to most persons; but as it is necessary to the elucidation of our subject, we will briefly repeat it. The internal membrane, or the lining coat of a calf's stomach, having been removed from the organ, is hung up, like a bladder, to dry; when required, a piece is cut off, put in a jug, a little warm water poured upon it, and after a few hours it is fit for use; the liquid so made being called rennet. A little of this rennet, poured into a basin of warm milk, at once coagulates the greater part, and separates from it a quantity of thin liquor, called whey. This is precisely the action that takes place in the infant's stomach after every supply from the breast. The cause is the same in both cases, the acid of the gastric juice in the infant's stomach immediately converting the milk into a soft cheese. It is gastric juice, adhering to the calf's stomach, and drawn out by the water, forming rennet, that makes the curds in the basin. The cheesy substance being a solid, at once undergoes the process of digestion, is separated into chyle by the bile, and, in a few hours, finds its way to the infant's heart, to become blood, and commence the architecture of its little frame. This is the simple process of a baby's digestion:-milk converted into cheese, cheese into chyle, chyle into blood, and blood into flesh, bone, and tegument-how simple is the cause, but how sublime and wonderful are the effects!
2458. We have described the most important of the three functions that take place in the infant's body-respiration and digestion; the third, namely, circulation, we hardly think it necessary to enter on, not being called for by the requirements of the nurse and mother; so we shall omit its notice, and proceed from theoretical to more practical considerations. Children of weakly constitutions are just as likely to be born of robust parents, and those who earn their bread by toil, as the offspring of luxury and affluence; and, indeed, it is against the ordinary providence of Nature to suppose the children of the hardworking and necessitous to be hardier and more vigorous than those of parents blessed with ease and competence.
2459. All children come into the world in the same imploring helplessness, with the same general organization and wants, and demanding either from the newly-awakened mother's love, or from the memory of motherly feeling in the nurse, or the common appeals of humanity in those who undertake the earliest duties of an infant, the same assistance and protection, and the same fostering care.
THE INFANT.
2460. We have already described the phenomena produced on the new-born child by the contact of air, which, after a succession of muscular twitchings, becomes endowed with voice, and heralds its advent by a loud but brief succession of cries. But though this is the general rule, it sometimes happens (from causes it is unnecessary here to explain) that the infant does not cry, or give utterance to any audible sounds, or if it does, they are so faint as scarcely to be distinguished as human accents, plainly indicating that life, as yet, to the new visitor, is neither a boon nor a blessing; the infant being, in fact, in a state of suspended or imperfect vitality,—a state of quasi existence, closely approximating the condition of a still-birth.
2461. As soon as this state of things is discovered, the child should be turned on its right side, and the whole length of the spine, from the head downwards, rubbed with all the fingers of the right hand, sharply and quickly, without intermission, till the quick action has not only evoked heat, but electricity in the part, and till the loud and sharp cries of the child have thoroughly expanded the lungs, and satisfactorily established its life. The operation will seldom require above a minute to effect, and less frequently demands a repetition. If there is brandy at hand, the fingers before rubbing may be dipped into that, or any other spirit.