Bile, the green and bitter liquid secreted by the liver. This liquid presents differences in the various classes of animals, although its principal characters are everywhere the same. Taken from the gall bladder, it is a mucous, viscous, somewhat transparent fluid, capable of being drawn out in threads of a green or brown color, of a bitter but not astringent taste, sometimes leaving a rather sweet after-taste, and of a peculiar odor, often having when warmed the smell of musk. It is usually weakly alkaline, often perfectly neutral, and only in disease, in rare cases, acid. It differs from other animal juices in long resisting putrefaction, when the mucus mixed with it has been taken away. The chemical composition of bile is still but little known, the best chemists being in complete disagreement in this respect. However, there are some points which seem to be decided. For instance, there is in bile a resinous substance, which is a combination of one or two acids with soda; there is a coloring principle (the biliverdine), a peculiar fatty matter, the cholesterine, and other fatty substances, salts, and water.

According to Demarcay, the bile of oxen has the following composition:

Demarcay admitted only one acid in bile, and he considered this liquid as a fluid soap, resulting from the combination of this acid (cholic acid) with soda. Strecker has found that the cholic acid of the French chemist is a complex one, and he has shown that it is composed of two acids, one of which he calls cholic and the other choleic. According to the researches of Benson and Strecker. the choleate of soda is the chief principle of bile, as regards its relative quantity, and also its importance. The choleic acid is a nitrogenized substance, containing sulphur in greater proportion than the other nitrogenized matters. As in the bile of most animals sulphur exists only in the choleic acid, and in the proportion of 6 per cent., it is possible to ascertain easily the quantity of this acid in any kind of bile. It has thus been found that almost the whole of the alcoholic extract of bile consists in choleic acid in the fox, the sheep, the dog, &C, while in the bile of the ox there is as much cholic as choleic acid. The salts formed by these two acids amount to at hast 75 per cent, of the whole of the solid constituents of bile.

Normal human bile contains, according to Frerichs, about 14 per cent, of solid constituents; but Lehniann justly remarks that the quantity of water, and consequently the proportion of solid constituents, may be as variable in bile as in most of the other secretions. Gorup-Besanez found 9.13 per cent, of solid constituents in the bile of an old man, and 17.19 per cent, in that of a child aged 12 years; but many more proofs are necessary to determine that bile is more aqueous in old age than in childhood. Lehmann says that the organic constituents of human bile amount to about 87 per cent, of the whole solid residue. The proportion of the other elements of bile, i. e., bile pigment (bili-verdine), cholesterine, fats, and mineral salts, has not yet been positively determined. The two special organic acids of bile can be decomposed into various substances. They both, when treated by alkalies, give origin to cholalic acid, and to dyslysine, but one of them (the cholic aoid) produces also glycocoll, and the other (the choleic acid) taurine. When treated to powerful acids, cholic acid gives origin to choloidic acid, glycocoll, and dyslysine, while choleic acid produces taurine, choloidic acid, and dyslysine.

Cholesterine and margaric and oleic acids are kept in solution in bile by the two principal organic acids of this secretion. The biliverdine, or the coloring principle of bile, is a substance resembling in its composition the hematosine or coloring principle of blood. It contains nitrogen and iron, as do all the organic coloring matters, according to M. yerdeil. The biliary sugar, or picromel, seems to be only a product of decomposition of some of the constituents of bile. The biline of Ber-zelius and Mulder seems to be a mixture of alkaline cholates and choleates. - The ancient physicians and physiologists used to consider the organ which secretes bile, the liver, as a most important one; but after Aselli, in 1622 bad discovered the lymphatic vessels, a reaction took place against the importance attributed to the liver, and some physiologists went so t.»r as to think that its share in the vital actions was almost null. In France the researches of many physiologists, and particularly of Prof Bernard, have shown that the liver is one of our most important organs, and recent experiments have proved that bile is a very useful secretion, if not an essential one.

Schwann opened the abdomen and the gall bladder in many dogs, and succeeded in forming a biliary fistula, after having tied the bile duct. Nine of these animals very quickly died; six lived 7, 13, 17, 25, 64, and 80 days; two only survived definitively, but in them a new bile canal was formed. Of the six dogs that lived from 7 to 80 days, four seemed to die starved, having lost their fat. The two others after a few days began to regain their fat, and reached their initial weight up to a certain time, when they became again emaciated and finally died. Blondlot has seen a dog living five years after the occlusion of the bile duct, and the formation of a biliary fistula, through which the bile flowed out. During this long period the health of the animal was usually very good. More recently Schwann has repeated his experiments on 20 dogs, out of which only two survived, one four months, and another a year. Nasse kept a dog alive five months with a biliary fistula. Its appetite was good, and it ate about double the quantity of meat that a healthy dog of the same size would have taken, and nevertheless it died almost completely deprived of fat.

It results from very careful experiments of Bidder and Schmidt, and of their pupil Schell-bach, that the cause of death, when bile is not allowed to flow into the bowels and passes out of the body, is that the animal has a great difficulty in repairing the loss of fat and of ni-trogenized substances which go out with the bile. In a dog operated upon by these physiologists, the quantity of food taken was much greater than before the operation, and the consequence was that the animal did not lose his forces and remained fat, though less so than before. Prof. Bernard, according to Dr. Por-chat, has ascertained that if adult dogs may live many months when bile flows out of their body by a biliary fistula, it is not so with young dogs, in which death always occurs quickly in such circumstances. Some facts observed in men (in children by Dr. Porchat, in adults by Dr. Budd) seem to prove also that adults may live much longer than children when there is no bile passing into the bowels. It seems very probable that bile is not absolutely necessary to digestion, as some animals have lived a long while without bile; but even in these cases there is room for doubt.

For instance, Blond-lot's dog was not prevented licking its wound, and probably swallowed a little bile, as Schwann has seen his dogs doing; and Bidder and Schellbach, we cannot understand why, at times gave pieces of liver (containing bile) as food to the one of their dogs that was the least affected by the operation. We may sum up thus: 1. Bile has not yet been positively proved not to be absolutely necessary to digestion and to life. 2. It seems probable, however, that its function is not absolutely essential. 3. When bile is missing in the bowels (and flowing out of the body by a fistula), the principal cause of death is the loss of fat and of albuminous matters. We will add to this last conclusion that, according to Dr. Brown-Sequard, it would be very important to repeat the experiments of Blondlot, Bidder, and others, in trying to repair by food the loss of certain materials of the body which go out with bile, and which are not present in sufficient amount in meat and bread. Among these materials sulphur is the principal, and it would be easy to give a great deal of it by feeding the animals upon eggs and other kinds of food which contain more sulphur than meat and bread.

This view of Dr. Brown-Sequard is grounded not only on the fact that bile flowing out of the body takes away a great quantity of sulphur and other principles, but also that when bile passes freely into the bowels, its elements, and particularly soda and sulphur, according to Liebig, are absorbed. - A question which is intimately connected with that we have examined already concerning the importance of bile, is whether this liquid is to be considered as an excrement or as a useful secretion. It appears to be certain that some, at least, of the principles of bile are absorbed in the bowels, if not most of them, as Liebig thought, and that therefore bile cannot be said to be entirelv an excrement. However, some of the compound constituents of bile are transformed in the bowels, as Mulder and Frerichs have shown, and they are expelled with the fecal matters. We are consequently led to conclude that bile is only partly an excrement, if it is so at all. We say if it is so, because the part of it which is expelled with the fecal matters may have some use before being expelled. - The fact that there is a very great quantity of bile secreted in a day throws some light on the question of its reabsorption.

Blondlot says that a dog of a medium size secretes from 40 to 50 grammes (nearly 1 1/2 ounce) a day. Nasse and Platner speak of 200 grammes (6 1/2 ounces) as the secretion of bile in a dog weighing 10 kilogrammes (22 lbs.), which gives a proportion of 1 to 50. Bidder and Schmidt have found that the quantity of bile varies extremely with the species of the animal experimented upon. While for each 2 pounds of the body of a cat there is a secretion of 14 grammes (1/2 ounce) of bile in a day, in the dog there is almost 20 grammes (2/3 ounce), in the sheep 25 1/2 grammes (5/6 ounce), and in the rabbit the enormous quantity of 136 grammes (4 1/2 ounces). In weighing the solid residue of the fecal matters of a dog for many days, and comparing the result obtained in so doing to the weight of the solid residue of bile during the same time, Bidder and Schmidt have found that the two quantities were nearly alike, so that necessarily a good part of the principles of bile is absorbed in the bowels. They have also ascertained that almost all the sulphur of the bile is absorbed.

They think that only a small quantity of bile, transformed into an insoluble substance (dyslysine), remains unabsorbed and goes out with the excrements. - Sylvius de la Boe, and afterward Boerhaave, imagined that bile is employed to neutralize the product of gastric digestion, chyme, which is very acid. This view has been considered quite wrong by almost every one, but Lehmann justly remarks that there is some truth in it, and he affirms that bile certainly contributes to the neutralization of the free acids of chyme. Bile no doubt acts as a solvent of fat, at least by one of its constituents, the choleate of soda, as has been shown by Strecker, although Bidder and Schmidt have found no difference in the quantity of fat absorbed, whether the bowels contained bile or not. But their mode of deciding this question is open to many objections. It has been said that bile prevents putrefaction taking place in chyme, or at least in fecal matters. Most of the recent experimenters agree with Tiede-mann and Gmelin in admitting this influence of bile.

Dr. Porchat has observed, in children in whom bile could not pass in the bowels on account of the occlusion of the bile duct, that the fecal matters were putrefied, as Bidder and Schmidt, Frerichs, and others, have observed in animals in which they had tied this duct. However, it seems that in some cases the absence of bile is not sufficient to allow putrefaction to take place in the fecal matters, as Blondlot says that he has observed no difference between these matters in dogs in good health and in those operated upon. The water contained in bile helps in the dissolution of certain elements of chyme, and in so doing renders their absorption more easy. - Bile acts as an excitant on the mucous membrane of the bowels, to produce reflex contractions, favoring in this way the propulsion of food and of fecal matters. According to Schiff', bile produces contractions in the intestinal villi. It is said also that bile increases the secretion of the intestinal mucus, and prevents constipation. All these views may be partly true, but it is certain that without bile the expulsion of fecal matters takes place regularly. - Many physiologists think that bile, like most of the secretions, contains some effete matters which cannot be of any use in the blood, or which might be deleterious.

In opposition to the views of those who admit that the secretion of bile is for the purpose of purifying the blood, and who still regard this liquid merely as an effete carbonaceous matter which the respiration has not removed, Lehmann says that the bile - a secretion by no means poor in nitrogen and hydrogen - is not separated in any increased quantity when the process of oxidation in the lungs happens to be disturbed; that there are no pathologico-anatomical facts which favor the view that the liver can act vicariously for the lungs; and, lastly, that the separation of carbon by the liver, as compared with that by the lungs, is so trifling, as shown by Bidder and Schmidt, that the liver can hardly be regarded as essentially a blood-purifying organ, in so far as the elimination of carbon is concerned. However, it is certain that when bile is not excreted freely in man, jaundice, and frequently certain nervous disturbances, are produced, and these phenomena must be attributed to the action of some of its principles. But three explanations may be given concerning the production of these phenomena, and we do not yet positively know which is tbe best.

In the first place, it may be that the principles of bile preexist in the blood, and that when they are not secreted, their quantity increasing, they produce the deleterious influence which sometimes results in jaundice; in the second place, they may be secreted, and, in consequence of some obstruction of the bile duct, they may be absorbed, and then produce their ill effects; in the third place, they may be changed into toxical substances either in the blood or in the liver or the biliary ducts. As regards the first of these views, Lehmann lias tried to prove, on good grounds, that the secretion of bile is not, like the urinary secretion, a mere separation of certain principles from the blood; and therefore we may conclude that it is not probable that bile, even if it contains toxical substances, results from a depuration of the blood. If we admit the second view, that the liver produces most of the principles of bile, and that these principles are absorbed in cases of jaundice, we find that we cannot explain the toxical phenomena which then sometimes take place, because they are not constant, and they exist in cases where jaundice is or is not very considerable, while they may not appear in cases of deep jaundice.

J)r. Budd has been led to the third view above stated, which is that poisonous substances are formed in the blood from the principles of bile. The function of depuration of the blood, attributed to the liver, seems therefore to be of much less importance than some persons have thought. Dr. Budd relates several cases in which the passage of bile into the bowels was entirely prevented by the complete closure of the bile duct, and in which, nevertheless, life was prolonged for many months. We must say, however, that the secretion of substances which may, when they are absorbed, and when they accumulate in the blood, be transformed into a poison, ought in some respects to be considered as a depuration. - It has been a much debated question whether bile is secreted from the blood of the portal vein or that of the hepatic artery. Experiments on animals and pathological facts have been mentioned in favor of both these opinions. When a ligature is placed on the portal vein, bile not only continues to be secreted, but the other functions of the liver also continue; but this fact, as Brown-Sequard remarks, cannot prove that the blood of the portal vein is not necessary for these functions, as this blood after the ligature passes into the vena cava, and afterward into the arterial circulation, and therefore into the liver, by the hepatic artery.

It seems very probable, indeed, from the great quantity of bile produced in a day, that the portal blood, if not the only source of the secretion of bile, is at least employed in a great measure for this secretion.