474 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 



which are formed in bacterial decomposition ; 1 and the products yielded 

 by the bile, stercobilin, cholesterin, and traces of bile acids. 2 



Stercobilin* is a reduction compound of the bile pigments formed 

 in their passage along the intestine, and is probably identical with 

 urobilin and hydrobilirubin. Normally, all the bile pigment is reduced 

 to this substance, but bilirubin has been observed in the faeces under 

 pathological conditions. 



Excretine is a crystalline body, described by Marcet 4 as occurring 

 only in human fasces. It is very soluble in boiling alcohol, and may be 

 mechanically thrown down from an alcoholic extract of the fasces by 

 adding milk of lime. The precipitate is washed with water, dried and 

 extracted with a mixture of alcohol and ether. On concentration of the 

 solution by evaporation, impure exqfetine crystallises out. This is 

 dissolved in hot alcohol, decolorised by animal charcoal, and obtained 

 pure on r eery stal lisa tion in acicular four-sided prisms, melting at 92- 

 96 C. It is insoluble in water, hot or cold ; sparingly soluble in cold, 

 readily in hot alcohol ; very soluble in ether ; and the solutions are 

 neutral in reaction. Its quantitative composition gives the formula 

 C 78 H 156 S0 2 . Hinterberger 5 states that, by repeated crystallisation, it may 

 be obtained free from sulphur, and then has the empirical formula 

 C 20 H 30 ; with bromine this yields a substitution compound, C 20 H 34 Br 2 0. 



Excretoleic acid is a body described by Marcet, 6 who obtained it on 

 cooling a hot alcoholic solution of human fasces. On exhausting with 

 ether, a green ethereal solution is obtained, which, on evaporation, leaves 

 an oily residue of a dark green colour and acid reaction, melting at 

 25-26 C. 



Meconium is the name given to the contents of the large intestine in 

 the foetus, which are expelled at, or after, birth. It is a dark brownish- 

 green mass of acid reaction. It contains 20 to 30 per cent, of dried 

 solids, which consist of mucin, bile pigments (biliverdin and bilirubin), 

 bile acids, cholesterin, fats, fatty acids, calcium and magnesium phos- 

 phates and sulphates. 



In addition it contains a substance giving two absorption bands, one 

 to the red side of the D line, and the other, broader and darker, between 

 the D and E lines. 



1 The odour of the fneces arises from these bodies. - See p. 391. 



3 Vanlair and Masius, CcntralU. f. d. med. JVissensch. , Berlin, 1871, No. 24, S. 369; 

 see also under "Bile," p. 388. 



4 Med. Times and Gaz., London, 1858, 1ST. S., vol. xvii. p. 156. 



5 Ann. d. Chem., Leipzig, 1873, Bd. clxvi. S. 213. 6 Loc. tit. 



