O'n with the dance! let jóy! be unconfìned! And nearer, clearer, deadlier than before! Within a windowed nichel of that high háll' And caught its tónel with Death's prophetic èar; Ah! then and there was hurrying to and fró, And gathering téars, and tremblings of distrèss, And cheeks all pàle, which but an hour ago1 Blùshed at the praise of their own lòveliness: And there were sudden pàrtings, such as press The life from out young hearts, and choking sighs Which ne'er might be repeated; who could guess' If ever mòre should meet those mutual eyes, Since upon night so sweet! such awful mòrn could risc? And there was mounting in hot hàste: the stèed, Or whispering, with white líps-"The foe! they come! they come!" And wild and high the "Camerons' gathering" rose ! Have heard—and heárd, too, have her Sàxon foes: The stirring mémory of a thousand years; And 'Evan's, Dónald's fame, rìngs in each clansman's ears! And Ardennes waves above them' her green leaves, Ere évening to be trodden like the gràss, Which now beneath them, but above shall grow In its next verdure; when this fiery mass Of living válour, ròlling on the fóe, And burning' with high hópe, shall moulder! cóld and lòw! Last noon' beheld them full of lusty life, The thunder-clouds' close d'er it, which, when rént, BYRON. PART II. SECTION IV. WASTE AND REPAIR OF THE BODY. Aerate, (aër, G.) to change by the agency | Gastric, (gaster, G.) belonging to the of air. Aorta, (aorte, G.) Artery, (aer, tereo, G.) so called because Assimilated, assimilation, (ad, similis, Auricle, (auricula, auris, L.) Lit. the Capillaries, (capillus, L.) Lit. hair-like Chyle, (chylos, cheo, G.), Follicle, (folliculus, follis, L.) Lit.a little stomach. Gullet, (gula, L.) Lacteals, (lac, L.) Lit. the milk-like vessels. Mucous, (mucus, L.) slimy; a mucous membrane is one which secretes a slimy substance. Pancreas, (pas, creas, G.). Lit. all Saliva, (L.) the spittle. Ventricle, (ventriculus, venter, L. Lit. DIGESTION. Ir is a peculiar excellence of the organic machinery of living creatures, that it keeps itself in repair. The living fabric, in the very actions which constitute its life, is every moment yielding up its particles to destruction, like the coal which is burned in the furnace; so much coal to so much heat, so much waste of the tissues of the body to so much vital activity. You cannot wink your eye, move your finger, or think a thought, but some minute particle of your substance must be sacrificed in doing so. This unceasing waste implies a necessity for equally constant repair, and the materials of that repair must come from without. Unless the coal which is burning be from time to time replaced, the fire soon smoulders, and finally goes out; unless the substance of your body which is ever wasting, be from time to time furnished with fresh food, life flickers, and at length becomes extinct. Food, then, is intended to repair the body's never-ceasing waste; it is the coal which feeds the flame of life. It is derived from without, from the animal and vegetable creation around us; and, entering the body by the mouth, is transformed and assimilated, that is, changed into the same substances, bone, muscle, nerve, &c., of which the body is itself composed. The digestion of the food, which is preparatory to its being thus assimilated, commences in the mouth. There a somewhat complicated action takes place. The tongue, cheeks, and jaws, by means of their numerous muscles, roll the food about in the mouth, and keep it between the teeth, which act as a mill to tear and grind it. Meanwhile, it is moistened by the saliva, a tasteless fluid, manufactured by six very small bags or pouches, called glands, situated in the mucous membrane which lines the mouth. The saliva, besides moistening the food, has also a chemical effect of great importance to digestion. Food swallowed without proper mastication may no doubt be digested by a vigorous stomach, but there is just as little doubt that the duties of the latter organ are greatly, perhaps unsafely, increased, when due time is not allowed for the action of the saliva. Hence our meals should not be eaten too hurriedly. The contents of the mouth are carried to the stomach by a pipe called the gullet, which extends from the back of the mouth downwards through the neck and body. Great care is taken, by means of valves or lids, to prevent the smallest morsel of the masses so swallowed from entering the windpipe, or any of the other tubes that open into the cavity behind the mouth. Every one knows that, when such an accident does happen, it is exceedingly disagreeable, and, if not speedily remedied, may be fatal. As soon as the food enters the stomach, it is subjected to new processes, similar in some degree to those which it has already undergone. The stomach is a large pouch, resem bling in shape the wind-bag of a bagpipe. It is lined, like the mouth, with a mucous membrane, soft as velvet, which is studded all over with minute finger-like glands, called follicles. From these is poured into the cavity of the stomach, at the rate of about thirty pounds daily in a healthy man, the gastric juice, a fluid which may be regarded as the chief agent in digestion. This juice mingles with the food, upon which it acts chemically, gradually reducing it to a liquid or soluble state. Meanwhile the whole mass is turned round and round, by the contractions of a muscular coating which surrounds the stomach, immediately beneath the mucous lining already mentioned. By this churning, as it has been happily called, the solid parts are not only well ground, but thoroughly mixed with the gastric juice. The food is now reduced to a thin pulp, but the process of its digestion is not yet complete. It leaves the stomach as chyme, and enters the intestines. Though usually spoken of as consisting of several parts, the intestines really form one continuous tube or canal, above thirty feet in length, or nearly six times the length of the body. It is coiled up, like a huge serpent, in the abdomen. The chyme, as it traverses this canal, meets with three new liquids, which greatly alter its character. These are the bile, formed by the liver, the pancreatic juice, which comes from the pancreas, or sweet-bread, and the intestinal juice, the product of certain glands in the lining of the intestine itself. By the action of these various substances, the chyme, or at least all that is nutritious in it, is gradually converted, in its progress through the folds of the intestine, into a milklike substance called chyle. Another process now commences. The chyle, thus gradually formed in the intestine, is sucked up by an immense number of minute vessels or tubes, into which it penetrates, by oozing or soaking through the walls of the intestine. Some substances, such as water, may be absorbed in the stomach itself, but these are exceptional. Absorption usually takes place in the intestine. The absorbent vessels are named lacteals, from their colour when filled with chyle. |