THE LIVER SECRETION OF BILE. 477 



Bile is a viscid, neutral or feebly-alkaline, somewhat oily-looking; liquid, 

 of a greenish-yellow color, and very bitter taste, followed by a sweetish after- 

 taste. It is readily miscible with water, and in solution froths like one of 

 soap. Its specific gravity in the human subject is about 1018, the extremes 

 being 1.0105 and 1.032. According to Kowalewsky ' the pressure of the 

 Bile in the ductus communis choledochus under ordinary circumstances in 

 curarized cats, varies from 3. 5 to 7.5 mm. of mercury (2-4 in. of water), 

 rising if the duct be ligatured to from 12 to 20 mm. of mercury (6-11 in. of 

 water). Heidenhain states that it is secreted under a pressure of a column 

 of water, eight inches in height. The proportion of solid matter which it 

 contains is usually from 9 to 17 per cent., and nearly the whole of this con- 

 sists of substances peculiar to Bile. 100 parts of human Bile purified and 

 dried at 230 F. contain about 1.5 parts of sulphur. Bogoljubow observes 

 that whilst freshly secreted Bile may contain as much as 64 per cent, of 

 combined and 7 per cent, of free carbonic acid, the Bile which has long been 

 stored up in the gall-bladder of fasting animals, may not contain more than 

 2 per cent, of the combined and 2 per cent, of the free gas. In the biliary 

 matter, according to the researches of Strecker (which are undoubtedly the 

 most accurate and satisfactory that have been hitherto made), the following 

 substances may be distinguished : Tw.o resinous acids, the Glycocholic (which 

 is the cJwllc acid of Strecker) in small quantity, and the Taurocholic (which 

 is the choleic acid of Strecker, and is nearly the same with the biliu of other 

 chemists) ; these are formed, according to Lehmaun, by the " conjugation" 

 of cholic acid with glycin or glycocoll (gelatin-sugar) and taurin respec- 

 tively ; and they are united in the bile with soda as a base. It is in the 

 taurocholic acid that the sulphur of the bile presents itself, no less than 25 

 per cent, of that element existing in taurin ; so that the proportion which 

 this acid bears to the glycocholic (which differs greatly in different animals) 

 may be estimated by the amount of sulphur in the mixture of the two. 2 Be- 

 sides a variable quantity of the ordinary Fatty acids, Bile also contains Clio- 

 lesterin, a non-sapouifiable crystalline fatty substance; Lecithin, C 44 H 90 NO 9 ; 

 various products of the disintegration of albumen, as Leucin, Ty rosin, Xau- 

 thin, and Hypoxanthin ; and Cholin or Neurin, 3 C 5 H 15 NO 2 , which is one of 

 the products of decomposition of Lecithin, and certain coloring matters, the 

 nature of which has not been very accurately determined, for Stadeler (1863) 

 isolated five distinct compounds: Bilifulviu, Biliverdin, Bilifusciu, Bilipras- 

 cin, and Bilihumin: whilst Maly 4 (1864) finds only one substance, Chole- 

 pyrrhin ; and Dr. Thudichum 5 (1872) describes two. Cholophpeiu or Biliru- 

 bin, C 9 H 9 NO 2 , and Bilifusciu, C 9 H n N0 3 . The relationship of these coloring 

 matters to the coloring matter of the Blood, first suggested by Virchow, 6 has 

 been rendered probable by the discovery of Zenker 7 of crystals of Hsema- 

 toidin in inspissated Bile, by the circumstance that both contain iron, and by 

 the observation of Gu'bler 8 that Bilirubin and Htematin give the same play 

 of colors with NO S , except that the green color is most persistent in the 

 former and the violet in the latter. R. Maly 9 has pointed out that there is 



1 Pfliiger's Archiv, Bd. viii, Heft xii. 



2 For excellent accounts of the Liver and its Functions, see Dr. Dalton's Human 

 Physiology, 1871, and Austin Flint's Physiology of Man. 1870, vol. iii, p. 232. 



3 '0. Liebreich, Ruv. des COUPS Scient.," torn, v, p. 048, 1848. 



4 Bernard, Physiologic Generale, Revue Scientitique, 1873, p. 462. 



6 Clinical Physiology, 1872, p. 18 



6 Archiv f. Path. An at., Bd. i, 1848, p 421. 



7 Jahresbericht von der Gesellsch. f. Natur und Heilkunde in Dresden, 1858, p. 53. 



8 Gaz. Med. de Paris, 1859, p. 409. 



9 R. Maly, Centralblatt f. d. Med. Wiss., 1871, p. 849, and Annal. de Cheraie v. 

 Pharm., Bd. clxiii, p. 77, 1872. 



