FORMATION OF GALL-STONES. 77 



separation of cholesterin from the bile is still not explained, even 

 though mucus and pigment-lime can and must act as solid points. 

 The question suggests itself, whether the bile lying amongst the 

 gall-stones is normal in its character : it has been believed that it 

 presents nothing abnormal,* but no conclusions can be drawn 

 from any analyses of human bile that have yet been instituted, for 

 the quantity of bile obtained from a dead body is too small to 

 admit of an accurate analysis ; moreover, the constitution of the 

 bile when obtained after death, is generally more dependent on the 

 morbid process which gave rise to the fatal termination, than on 

 that which led to the formation of biliary concretions. It is, how- 

 ever, more than probable that in order that concretions of choles- 

 terin should be formed, the bile should contain a smaller amount 

 of the solvent for this substance than the normal fluid contains ; 

 but, as has been already mentioned, we very rarely meet with bile 

 in which there is a separation of minute tablets of cholesterin, 

 although they often occur in other fluids, as, for instance, dropsical 

 effusions, &c. ; hence the presence of solid insoluble particles must 

 be regarded as exercising a considerable influence on the formation 

 of gall-stones. If we inquire what it is which holds the cholesterin 

 and the pigment-lime in solution in normal bile, direct experi- 

 ments afford an answer to the question, and show that both these 

 substances are principally held in solution by taurocholic acid or 

 taurocholate of soda. If we digest the insoluble residue of a brown 

 gall-stone with taurocholic acid or acid taurocholate of soda, it is 

 entirely dissolved with the exception of a few greyish-white flocculi, 

 and the previously colourless solution assumes the tint of fresh 

 bile. Strecker showed long ago that cholesterin was soluble in 

 solutions of taurocholic acid and its salts. Glycocholic and cholic 

 (Strecker's cholalic) acids possess this property in a far less degree. 

 The question regarding the formation of gall-stones would be very 

 readily answered if it could be proved that bile which has a ten- 

 dency to form concretions, was either poor in taurocholic acid ic 

 relation to cholesterin and pigment-lime, or that its taurocholic 

 acid was decomposed in the gall-bladder and had thus lost its 

 power of dissolving these two substances. 



Since concretions, which are rich in cholesterin, are never 

 entirely devoid of pigment-lime, while, on the other hand, calculi 

 which are poor in cholesterin, are always very rich in pigment- 

 lime, the idea suggests itself that this latter compound takes an 



* Novi comment, acad. sclent, inst. Bononiens. T. 3, p. 307-317. 



