"3. In disorders of the pancreas, we find that the fatty matters, contained in the food, pass entire in the evacuations."
The above is an extract from the report of a body composed of several members of the French Academy of Sciences. "M. Bernard" (continues the report) "has exhibited to us the first of these experiments, and has furnished us with the means of repeating it with the several varieties of the gastric juice. We have not the slightest doubt on the subject. It is incontestable that fatty substances are converted into an emulsion by this juice, in a manner easy and persistent, and it is no less true that the saliva, the gastric juice, and the bile are destitute of this property.
"The second demonstration can be given in various modes; but the author has discovered, in the peculiar arrangement of the digestive apparatus of the rabbit, an unexceptional means of obtaining it with the greatest precision, and at will. The pancreatic juice enters the intestinal tube of this animal about fourteen inches below the point where the bile is poured in. Now, as long as the food is above the region where it mixes with the pancreatic juice, there appears to be no formation and separation of a milky chyle; nothing shows that the fatty matters are reduced to an emulsion. On the contrary, as soon as the pancreatic juice mixes with the alimentary matters, we observe the fat to be converted into an emulsion, and a milky chyle to fill the corresponding lacteals. Nothing can give an idea of the result of these experiments, which have all the accuracy of a chemical operation performed in the laboratory, and all the beauty of the most perfect injection.
"We are not, therefore, surprised that divers pathological cases, hitherto imperfectly understood, should come to confirm the views of M. Bernard, by proving that, in diseases of the pancreas, fatty matters have been observed to pass unchanged in the dejections.
"The committee cannot hesitate to conclude that the author has perfectly demonstrated his physiological propositions; that he has completed the general characters of the theory of digestion, and that he has made known the mode of formation of the fatty matter of the chyle, and the manner of the digestion of the fatty matters."
The Kidneys.—Their office is, to secrete from the blood the useless or excrementitious fluids in the form of urine. When the skin is obstructed, the secretion is augmented, and profuse perspiration lessens it. From a cavity in the centre of each kidney a canal or tube proceeds, by which the urine is conveyed into the bladder. These tubes are named ureters. As the ureters enter the bladder, they pass forward, a short distance between its coats; which effectually prevents the urine from taking a retrograde course. The urine is expelled by the muscular power which the bladder possesses of contracting upon its contents.
RESPIRATION AND STRUCTURE OF THE LUNGS.
The organs of respiration are the larynx, the trachea, or windpipe, bronchia, and the lungs.
The air is expelled from the lungs principally by the action of the muscles of respiration; and when these relax, the lungs expand by virtue of their own elasticity. This may be exemplified by means of a sponge, which may be compressed into a small compass by the hand, but, upon opening the hand, the sponge returns to its natural size, and all its cavities become filled with air. The purification of the blood in the lungs is of vital importance, and indispensably necessary to the due performance of all the functions; for if they be in a diseased state,—either tuberculous, or having adhesions to the pleura, their function will be impaired; the blood will appear black; loaded with carbon; and the phlebotomizer will have the very best (worst) excuse for taking away a few quarts with a view of purifying the remainder! The trachea, or windpipe, after dividing into smaller branches, called bronchia, again subdivides into innumerable other branches, the extremities of which are composed of an infinite number of small cells, which, with the ramifications of veins, arteries, nerves, and connecting membranes, make up the whole mass or substance of the lungs. The internal surface of the windpipe, bronchia, and air-cells, is lined with a delicate membrane, highly organized with blood-vessels, &c. The whole is invested with a thin, transparent membrane—a continuation of that lining the chest, named pleura. It also covers the diaphragm, and, by a duplication of its folds, forms a separation between the lobes of the lungs.