spleen liberates hæmoglobin from a certain number of corpuscles, and that this is carried in solution in the blood-plasma of the splenic vein to the liver, where it is seized by the cells and manufactured into bile-pigment. Anyone can easily disprove this statement for himself, as Professor Schäfer has recently done. If blood be collected from two vessels, say, the splenic vein and the carotid artery, and allowed to clot, the serum will in each case be found free from hæmoglobin. If the spleen takes any part at all in the elaboration of bile-pigment, it does not proceed so far as to liberate pigment from the corpuscles; it may, however, render the pigment there more readily separable by the liver-cells. Injection of an aqueous solution of bile-salts into the blood, according to Huppert, is followed by an increase of bile-salts in the bile; according to Socoloff, this is not the case. This is a very fair sample of the knowledge we possess on the formation of these salts. In all probability the bile salts (glycocholate and taurocholate of soda) when formed serve over and over again; we shall discuss this question again under the heading The Fate of the Biliary Constituents' (p. 687). For the present it will be sufficient to say that it is generally believed that the bile-salts in the intestine undergo breaking down, the simpler constituents so formed are absorbed, and taken to the liver again, where once more they serve for the building up of bile-salts. To the above general facts concerning the secretion of bile a few references to important experiments on which our knowledge is based may be here briefly added. Simultaneous ligature of the hepatic artery and portal vein abolishes the secretion (Röhrig).* If the hepatic artery be ligatured the portal vein alone supports the secretion (Schiff, Schmulewitsch, Asp'). Complete ligature of the portal vein rapidly causes death; but if the branch to one lobe be ligatured there is a slight secretion in that lobe, so that in this case the bile must be formed from arterial blood (Schmulewitsch, Asp). If the blood of the hepatic artery is allowed to pass into the portal vein which has been ligatured on one side, secretion continues (Schiff). Profuse loss of blood arrests the secretion. All conditions that cause contraction of the abdominal blood-vessels diminish the secretion; so also do all conditions that cause congestion or stagnation of the blood in the vessels of the liver (Heidenhain ). 1 Proc. Physiol. Soc. 1890, p. 9. 3 Pflüger's Archiv, iii. 598. 2 Arch. d. Heilkunde, v. 237. 4 Virchow and Hirsch, Med. Jahresb. vol. i. 1873, p. 143. 5 Italian papers referred to in Hoppe-Seyler's Physiol. Chem. p. 281. Ber. sächs. Akad. Wiss. 1868. 9 Studien des Physiol. Inst. Breslau, Heft ii. 7 Ibid. 1873. Χ Χ 2. THE CHARACTERS OF BILE AND ITS CONSTITUENTS The methods of obtaining bile are the following: After death it can be readily obtained from the gall-bladder. During life it can only be obtained by means of a biliary fistula; an incision is made in the abdomen, the common bile-duct is divided, and a cannula inserted into the end in connection with the liver; this cannula is brought through and fastened to the wound in the abdomen, which soon heals. In another method the gall-bladder is opened and stitched to the abdominal wound. The liver pours its secretion now not into the intestine, but outside the body altogether through the external opening. This operation was first performed in animals by Schwann; ' since then Blondlot, Bidder and Schmidt, Heidenhain, Schiff, and many others have studied the secretion, and the constituents of bile by the same method. A few cases have occurred in which by surgical interference a biliary fistula has been established in human beings; and in some of these the secretion has been carefully studied. The most important of these cases have been recorded by Ranke,3 v. Wittich, Monro," Jacobsen, Yeo and Herroun, Copeman and Winston, and Mayo Robson.9 6 8 4 In both Ranke's and Monro's cases a liver abscess caused a communication between the lung and the gall-bladder, and the bile mixed with bronchial mucus was coughed up. In v. Wittich's and Yeo's cases the patient was suffering from serious disease; Jacobsen says nothing regarding the health of his patient; Copeman's case is the most interesting of the series to the physiologist, as the woman was not only in good health, but actually gained weight though all the bile was discharged externally. The quantity of bile secreted.—The statements of different observers vary very much on this question. The quantity in the twenty-four hours secreted by a human being is put down as 652 c.c. by Ranke, 532-8 c.c. by v. Wittich, 374-5 by Yeo and Herroun, and 779-6 by Copeman and Winston, or 2-5 pints per diem in a man of 12 stone. In animals the following numbers from Bidder and Schmidt are sufficient to illustrate the great variations in different parts of the Arch. f. Anat. u. Physiol. 1844, p. 124. 2 Essai sur les fonctions du foie, Paris, 1846. 3 Die Blutvertheilung u. d. Thätigkeitswechsel der Organe, Leipzig, 1871; Grundzüge d. Physiol. d. Mensch. 4th edit. p. 324. 4 Pflüger's Archiv, iii. 781. 6 Ber. d. deutsch, chem. Ges, iv. 1026. 8 Ibid. x. 213. Cycl. Anat. und Physiol. iii. 180. 7 Journ. of Physiol. v. 116. 9 Proc. Roy. Soc. xlvii. 499. animal kingdom; the numbers given are in grammes per kilo. of bodyweight in the twenty-four hours. A number of observations have also been made as to the influence of drugs in promoting the flow of bile; but in these experiments, as in those of stimulating nerves, it is necessary, but not always practicable, to distinguish between the bilesecreting mechanism (the liver-cells) and the bile-expelling mechanism (the contractions of gall-bladder and bile-ducts). Mercuric chloride produces an increase of water and a diminution of the solids in the bile (Scott'). Calomel, mercuric chloride, and taraxacum are not able to promote a flow of bile (Bennett, Rutherford, Gamgee). These drugs, generally regarded as hepatic stimulants, probably act on the bile-expelling mechanism. Podophyllin, rhubarb, aloes, colchicum are probably true cholagogues (Rutherford and Vignal).3 Various laxatives act in rabbits as cholagogues (Röhrig). The constituents of the bile. The constituents of the bile are mucin, a mucin-like nucleo-albumin, the bile-salts proper (taurocholate and glycocholate of soda), the bile-pigments (bilirubin, biliverdin, &c.), small quantities of fats and soaps, cholesterin, lecithin, urea, and inganic salts, of which sodium chloride and the phosphates of iron, calcium, and magnesium are the most important; traces of copper are also stated to be present. Bile is a yellowish, or reddish-brown, or dark-green, transparent fluid. The cause of the variations in its colour is due to the preponderance of the red (bilirubin) or the green pigment (biliverdin). It has a musk-like odour, a bitter-sweet taste, and a neutral or faintly alkaline reaction. The bile removed from the gall-bladder is more concentrated than that intercepted on its way from the liver to the gall-bladder. There appear to be two reasons for this: first, during its stay in the gall-bladder a certain amount of its water is absorbed; and, secondly, there is added to it by the walls of the gall-bladder and larger ducts the substances which give it its viscidity (mucin and nucleo-albumin).5 The specific gravity of human bile from the gall-bladder is 1026 to 1032; that from a fistula 1010 to 1011 (Jacobsen). 1 Beale's Arch. of Medicine, October 1858. 3 Ibid. October to December 1875. 2 Brit. Med. Journ. 1869, p. 411. 4 Loc. cit. 5 The insufficiency of these explanations is, however, well pointed out by Yeo and Herroun, Loc. cit. p. 120. 676 Quantitative composition of human bile.--The following table, taken from Yeo and Herroun's paper (the particulars regarding Copeman's case have been added), gives the mean percentage of solids in human bile as found by various observers : Observer Mean percentage of Here the most striking fact is the low percentage of solids in fistulabile as compared with bladder-bile. This cannot be explained on the score of ill-health, for the percentage in the first two cases is about equal; it is only explicable partially by the fact that fistula-bile does not stay in the gall-bladder. The low percentage of solids is, as the next table shows, almost entirely due to want of bile-salts; this can be accounted for in the way first suggested by Schiff; that there is normally a bile circulation going on in the body, a large quantity of the bile-salts that pass into the intestine being reabsorbed and again secreted. Such a circulation would obviously be impossible in cases where all the bile is discharged to the exterior and so lost. The following table gives analyses of human bile, in the 2nd and 3rd columns of fistula-bile, in the 4th column presumably of normal bile. Fistula bile (case of Normal bile 1 Pflüger's Archiv, ix. 492. Lehrbuch d. physiol. Chem., by Gorup-Besanez, 3 Auf. p. 529. This table illustrates the fact that of the two bile-salts the glycocholate is the more abundant. Many other observers who have published analyses of human bile note the same fact. The proportion of the two bile-salts is thus given in percentages :— Quantitative composition of the bile of the lower animals.—The following tables are taken from Hoppe-Seyler's work on physiological chemistry (p. 302 et seq.) : Percentage composition of dog's bile (analyses by Hoppe-Seyler) : We see, as before, that the bile from the gall-bladder is more concentrated than that which is freshly secreted, and that this is chiefly shown in the percentage of bile-salts, which in the dog consist almost exclusively of taurocholate of soda. The small percentage of sodium chloride is due to the fact that the greater part of that salt was dissolved by the alcohol and not estimated. The amount of taurocholate present may be easily estimated from the amount of sulphur in the dry residue of the alcoholic extract, taurocholic acid being the only substance there that contains sulphur (see further p. 681). 1 Pflüger's Archiv, xii. 54. 2 Physiol. Chem. p. 301. |