4 7 4 CHEMISTR Y OF THE DIGESTIVE PR O CESSES. 
which are formed in bacterial decomposition ; x and the products yielded 
by the bile, stercobilin, cholesterin, and traces of bile acids. 2 
St, rodbilin 3 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*as occurring 
only in human faeces. It is very soluble in boiling alcohol, and may be 
mechanically thrown down from an alcoholic extract of the faeces 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 excretine crystallises out. This is 
dissolved in hot alcohol, decolorised by animal charcoal, and obtained 
pure on recrystallisation 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 166 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 3G O ; with bromine this yields a substitution compound, C.^ld^Bi^O. 
Excretoleic acid is a body described by Marcet, 6 who obtained it on 
cooling a hot alcoholic solution of human faeces. On exhausting with 
ether, a green ethereal solution is obtained, which, on evaporation, leaves 
an oilv 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 faeces avisos from these bodies. 2 See p. 391. 
3 Vanlair and Masius. Centralbl.f. d. med. Wissensch., Berlin, 1871, Xo. 24, S. 369; 
see also under " Bile," p. 388. 
4 Med. Times and Gaz., London, 1858, X. S., vol. xvii. p. 156. 
5 Aim. d. Clicm., Leipzig, 1873, Bd. clxvi. S. 213. 6 Loc. eit. 
