The change goes on in every minute point of the body, though in some parts much faster than in others; as set forth in the piquant and sprightly language of Dr. O. W. Holmes [Footnote: Atlantic Almanac, 1869, p. 40.], who, giving a vivid picture of the constant decay and renewal of the body, says:
"Every organized being always lives immersed in a strong solution of its own elements."
"Sometimes, as in the case of the air-plant, the solution contains all its elements; but in higher plants, and in animals generally, some of the principal ones only. Take our own bodies, and we find the atmosphere contains the oxygen and the nitrogen, of which we are so largely made up, as its chief constituents; the hydrogen, also, in its watery vapor; the carbon, in its carbonic acid. What our air-bath does not furnish us, we must take in the form of nourishment, supplied through the digestive organs. But the first food we take, after we have set up for ourselves, is air, and the last food we take is air also. We are all chameleons in our diet, as we are all salamanders in our habitats, inasmuch as we live always in the fire of our own smouldering combustion; a gentle but constant flame, fanned every day by the same forty hogsheads of air which furnish us not with our daily bread, which we can live more than a day without touching, but with our momentary, and oftener than momentary, aliment, without which we can not live five minutes."
"We are perishing and being born again at every instant. We do literally enter over and over again into the womb of that great mother, from whom we get our bones, and flesh, and blood, and marrow. 'I die daily' is true of all that live. If we cease to die, particle by particle, and to be born anew in the same proportion, the whole movement of life comes to an end, and swift, universal, irreparable decay resolves our frames into the parent elements."
"The products of the internal fire which consumes us over and over again every year, pass off mainly in smoke and steam from the lungs and the skin. The smoke is only invisible, because the combustion is so perfect. The steam is plain enough in our breaths on a frosty morning; and an over-driven horse will show us, on a larger scale, the cloud that is always arising from own bodies."
"Man walks, then, not only in a vain show, but wrapped in an uncelestial aureole of his own material exhalations. A great mist of gases and of vapor rises day and night from the whole realm of living nature. The water and the carbonic acid which animals exhale become the food of plants, whose leaves are at once lungs and mouths. The vegetable world reverses the breathing process of the animal creation, restoring the elements which that has combined and rendered effete for its own purposes, to their original condition. The salt-water ocean is a great aquarium. The air ocean in which we live is a 'Wardian case,' of larger dimensions."
It is found that the simple elements will not nourish the body in their natural state, but only when organized, either as vegetable or animal food; and, to the dismay of the Grahamite or vegetarian school, it is now established by chemists that animal and vegetable food contain the same elements, and in nearly the same proportions.
Thus, in animal food, carbon predominates in fats, while in vegetable food it shows itself in sugar, starch, and vegetable oils. Nitrogen is found in animal food in the albumen, fibrin, and caseine; while in vegetables it is in gluten, albumen, and caseine.
[Illustration: Fig. 55]
It is also a curious fact that, in all articles of food, the elements that nourish diverse parts of the body are divided into separable portions, and also that the proportions correspond in a great degree to the wants of the body. For example, a kernel of wheat contains all the articles demanded for every part of the body. Fig. 55 represents, upon an enlarged scale, the position and proportions of the chief elements required. The white central part is the largest in quantity, and is chiefly carbon in the form of starch, which supplies fat and fuel for the capillaries. The shaded outer portion is chiefly nitrogen, which nourishes the muscles, and the dark spot at the bottom is principally phosphorus, which nourishes the brain and nerves. And these elements are in due proportion to the demands of the body. A portion of the outer covering of a wheat-kernel holds lime, silica, and iron, which are needed by the body, and which are found in no other part of the grain. The woody fibre is not digested, but serves by its bulk and stimulating action to facilitate digestion. It is therefore evident that bread made of unbolted flour is more healthful than that made of superfine flour. The process of bolting removes all the woody fibre; the lime needed for the bones; the silica for hair, nails, and teeth; the iron for the blood; and most of the nitrogen and phosphorus needed for muscles, brain, and nerves.