by tying the common bile-duct, and then opening the fundus of the gall-bladder, so as to produce a biliary fistula, by which the whole of the bile was drawn off. By doing this operation, and collecting and weighing the fluid discharged at different periods, they came to the conclusion that the flow of bile begins to increase within two and a half hours after the introduction of food into the stomach but that it does not reach its maximum of activity till the end of twelve or fifteen hours. Other observers, however, have obtained different results. Arnold,' for example, found the quantity to be largest soon after meals, decreasing again after the fourth hour. Kölliker and Müller,' again, found it largest between the sixth and eighth hours. Bidder and Schmidt's experiments, indeed, strictly speaking, show only the time at which the bile is most actively secreted by the liver, but not when it is actually discharged into the intestine.

Our own experiments, bearing on this point, were performed on

d

Fig. 53.

DUODENAL FISTULA.-a. Stomach. b. Duodenum. c, c, c. Pancreas; its two ducts are seen opening into the duodenum, one near the orifice of

dogs, by making a permanent duodenal fistulæ, on the same plan that gastric fistulæ have so often been established for the examination of the gastric juice. (Fig. 53.) An incision was made through the abdominal walls, a short distance to the right of the median line, the floating portion of the duodenum drawn up toward the external wound, opened by a longitudinal incision, and a silver tube, armed at each end with a narrow projecting collar or flange, inserted into it by one extremity, five and a half inches below the pylorus, and two and a half inches below the orifice of the lower pancreatic duct. The

the biliary duct, d, the other a short distance other extremity of the tube was

lower down. e. Silver tube passing through the abdominal walls and opening into the duodenum.

left projecting from the external opening in the abdominal pa

rietes, the parts secured by sutures, and the wound allowed to heal.

In Am. Journ. Med. Sci., April, 1856.

2 Ibid., April, 1857.

After cicatrization was complete, and the animal had entirely recovered his healthy condition and appetite, the intestinal fluids were drawn off at various intervals after feeding, and their contents examined. This operation, which is rather more difficult than that of making a permanent gastric fistula, is nevertheless exceedingly useful when it succeeds, since it enables us to study, not only the time and rate of the biliary discharge, but also, as mentioned in a previous chapter (Chap. VI.), many other extremely interesting matters connected with intestinal digestion.

In order to ascertain the absolute quantity of bile discharged into the intestine, and its variations during digestion, the duodenal fluids were drawn off, for fifteen minutes at a time, at various periods after feeding, collected, weighed, and examined separately, as follows: each separate quantity was evaporated to dryness, its dry residue extracted with absolute alcohol, the alcoholic solution precipitated with ether, and the ether-precipitate, regarded as representing the amount of biliary matters present, dried, weighed, and then treated with Pettenkofer's test, in order to determine, as nearly as possible, their degree of purity or admixture. The result of these experiments is given in the following table. At the eighteenth hour so small a quantity of fluid was obtained, that the amount of its biliary ingredients was not ascertained. It reacted perfectly, however, with Pettenkofer's test, showing that bile was really present.

From this it appears that the bile passes into the intestine in by far the largest quantity immediately after feeding, and within the first hour. After that time its discharge remains pretty constant; not varying much from four grains of solid biliary matters every fifteen minutes, or sixteen grains per hour. The animal used for the above observations weighed thirty-six and a half pounds.

The next point to be ascertained with regard to this question is the following, viz: What becomes of the bile in its passage through the intestine? Our experiments, performed with a view of settling this point, were tried on dogs. The animals were fed with fresh meat, and then killed at various intervals after the meals, the abdomen opened, ligatures placed upon the intestine at various points, and the contents of its upper, middle, and lower portions collected and examined separately. The results thus obtained show that, under ordinary circumstances, the bile, which is quite abundant in the duodenum and upper part of the small intestine, diminishes in quantity from above downward, and is not to be found in the large intestine. The entire quantity of the intestinal contents also diminishes, and their consistency increases, as we approach the ileocæcal valve; and at the same time their color changes from a light yellow to a dark bronze or blackish-green, which is always strongly pronounced in the last quarter of the small intestine.

The contents of the small and large intestine were furthermore evaporated to dryness, extracted with absolute alcohol, and the alcoholic solutions precipitated with ether; the quantity of ether precipitate being regarded as representing approximatively that of the biliary substances proper. The result showed that the quantity of this ether precipitate is, both positively and relatively, very much less in the large intestine than in the small. Its proportion to the entire solid contents, is only one-fifth or one-sixth as great in the large intestine as it is in the small. But even this inconsiderable quantity, found in the contents of the large intestine, does not consist of biliary matters; for the watery solutions being treated with sugar and sulphuric acid, those from both the upper and lower portions of the small intestine always gave Pettenkofer's reaction promptly and perfectly in less than a minute and a half; while in that from the large intestine no red or purple color was produced, even at the end of three hours.

The small intestine consequently contains, at all times, substances giving all the reactions of the biliary ingredients; while in the contents of the large intestine no such substances can be recognized by Pettenkofer's test.

The biliary matters, therefore, disappear in their passage through the intestine.

In endeavoring to ascertain what is the precise function of the bile in the intestine, our first object must be to determine what part, if

any, it takes in the digestive process. As the liver is situated, like the salivary glands and the pancreas, in the immediate vicinity of the alimentary canal, and like them, discharges its secretion into the cavity of the intestine, it seems at first natural to regard the bile as one of the digestive fluids. We have previously shown, however, that the digestion of all the different elements of the food is provided for by other secretions; and furthermore, if we examine experimentally the digestive power of bile on alimentary substances, we obtain only a negative result. Bile exerts no special action upon either albuminoid, starchy, or oleaginous matters, when mixed with them in test-tubes and kept at the temperature of 100° F. It has therefore, apparently, no direct influence in the digestion of these substances.

Furthermore it appears, from the experiments detailed above, that the secretion of the bile and its discharge into the intestine are not confined to the periods of digestion, but take place constantly, and continue even after the animal has been kept for many days without food. These facts would lead us to regard the bile as simply an excrementitious fluid; containing only ingredients resulting from the waste and disintegration of the animal tissues, and not intended to perform any particular function, digestive or otherwise, but merely to be eliminated from the blood, and discharged from the system. The same view is more or less supported, also, by the following facts, viz:

1st. The bile is produced, unlike all the other animal secretions, from venous blood; that is, the blood of the portal vein, which has already become contaminated by circulation through the abdominal organs, and may be supposed to contain disorganized and effete ingredients; and

2d. Its complete suppression produces, in the human subject, symptoms of poisoning of the nervous system, analogous to those which follow the suppression of the urine, or the stoppage of respiration, and the patient dies, usually in a comatose condition, at the end of ten or twelve days.

The above circumstances, taken together, would combine to make it appear that the bile is simply an excrementitious fluid, not necessary or useful as a secretion, but only destined, like the urine, to be eliminated and discharged. Nevertheless experiment has shown that such is not the case; and that, in point of fact, it is necessary for the life of the animal, not only that the bile be secreted and discharged, but furthermore that it be discharged into the

intestine, and pass through the tract of the alimentary canal. The most satisfactory experiments of this kind are those of Bidder and Schmidt,' in which they tied the common biliary duct in dogs, and then established a permanent fistula in the fundus of the gall-bladder through which the bile was allowed to flow by a free external orifice. In this manner the bile was effectually excluded from the intestine, but at the same time was freely and wholly discharged from the body, by the artificial fistula. If the bile therefore were simply an excrementitious fluid, its deleterious ingredients being all eliminated as usual, the animals would not suffer any serious injury from this operation. If, on the contrary, they were found to suffer or die in consequence of it, it would show that the bile has really some important function to perform in the intestinal canal, and is not simply excrementitious in its nature.

The result showed that the effects of such an experiment were fatal to the animal. Four dogs only survived the immediate effects of the operation, and were afterward frequently used for purposes of experiment. One of them was an animal from which the spleen had been previously removed, and whose appetite, as usual after this operation, was morbidly ravenous; his system, accordingly, being placed under such unnatural conditions as to make him an unfit subject for further experiment. In the second animal that survived, the communication of the biliary duct with the intestine became re-established after eighteen days, and the experiment consequently had no result. In the remaining two animals, however, everything was successful. The fistula in the gall-bladder became permanently established; and the bile-duct, as was proved subsequently by post-mortem examination, remained completely closed, so that no bile found its way into the intestine. Both these animals died; one of them at the end of twenty-seven days, the other at the end of thirty-six days. In both, the symptoms were nearly the same, viz., constant and progressive emaciation, which proceeded to such a degree that nearly every trace of fat disappeared from the body. The loss of flesh amounted, in one case to more than twofifths, and in the other to nearly one-half the entire weight of the animal. There was also a falling off of the hair, and an unusually disagreeable, putrescent odor in the feces and in the breath. Notwithstanding this, the appetite remained good. Digestion was not essentially interfered with, and none of the food was discharged

Op. cit., p. 103.