234 CONJUGATED ACIDS. 



of perfect freshness, and the little taurocholic acid that was origi- 

 nally present is decomposed before we commence our investiga- 

 tions. When we suspect that this acid is present, and have detected 

 biliary matter by Pettenkofer's test in the alcoholic extract, we 

 may hope to find taurine in the aqueous extract, which, however, 

 contains it in such small quantity, and often so intermingled with 

 other substances, that its recognition, even under the microscope, 

 is extremely difficult. We must not attempt to determine the 

 presence of sulphur as a test for taurocholic acid or taurine in the 

 aqueous extract, for this contains both sulphates and other 

 sulphurous organic bodies. 



Physiological Relations. 



Occurrence. From the determinations of the amount of sulphur, 

 instituted by Bensch* and others, we may conclude that taurocholic 

 acid exists not only in the bile of the ox, but in that of the fox, 

 bear, sheep, dog, wolf, goat, and certain birds and fresh-water fish ; 

 it has been found in the bile of the frog by Kunde and myself ; and 

 that it exists in human bile can hardly be doubted, since, as Gorup- 

 Besanez was the first to prove, taurine may be exhibited from it. 

 It might almost be inferred, from the numerical results obtained by 

 Schlieperf- in his analysis of the purified bile of a Boa Anaconda, 

 that the liver of this serpent secretes taurocholic alone, and none 

 of the other known biliary acids. That this acid is almost entirely 

 absent in the bile of the pig, as shown by the investigations of 

 Strecker, has been already mentioned. 



Unchanged taurocholic acid has not yet been found in any 

 other animal fluid ; but from the experiments of Kunde to which I 

 have already referred (p. 227), it is not improbable that it also 

 occurs in the blood. 



Origin. We have very little to say in the present place re- 

 garding the production of taurocholic acid : what has been already 

 stated respecting the formation of cholic acid (p. 126), of taurine 

 (p. 182), and of glycocholic acid (p. 227), is equally applicable 

 to the acid under consideration. As it has not yet been found in 

 the blood, it is impossible to decide chemically whether it be 

 primarily formed in the liver from its proximate constituents, or 

 whether it proceeds from the general metamorphosis of the non- 

 nitrogenous and nitrogenous animal matters. 



Uses. Since we are as ignorant of the chemical changes which 



* Aim d. Ch. u. Pharm. Bd. 65, S. 194-203. 

 t Ibid. Bd. CO, 8. 109-112. 



