CHEMISTRY OF THE LIVER. 



fuge. The addition of a little acetic acid produces likewise a 

 precipitate. It is, however, practically impossible to secure 

 pure mucin in this way as other bodies are carried down with 

 the precipitates and their subsequent separation is difficult. 

 The mucin of human bile is said to be nearly pure, while that 

 of other animals is mixed with nucleo albumins. 



BILE CONCRETIONS. GALL STONES. 



Under conditions not well understood a precipitation of cer- 

 tain constituents of the bile may occur in the gall bladder. 

 These precipitations take the form of solid masses which some- 

 times grow to considerable size, by gradual surface additions. 

 In every case the deposited material is built up in layers, often 

 well clehned, around some body as a nucleus. Three general 

 classes of such calculi are recognized. In man balls of choles- 

 terol, more or less pure, are the most abundant while pigment 

 stones are also frequently found. These pigment stones con- 

 tain essentially bilirubin in combination with calcium, the 

 alkali earth salts of the pigments being insoluble. The center 

 of the cholesterol stone may be a nucleus of bilirubin calcium. 

 Pigment stones are common in the gall bladders of cattle. 

 Finally we have stones consisting of calcium phosphate or 

 carbonate, which however, are not usual in man. 



The following analyses made of gall-stones of very different 

 appearance, illustrate the composition of the cholesterol stones 

 in man : 



Water (at 100 ) 4.60 4.50 



Cholesterol (and trace of fat) 90.87 90.08 



Bilirubin (CHCls extraction) 0.81 ) 0.19) 



Biliverdin (C 2 H 6 O extraction) 2.24 / 3 " 5 1.58 / I<77 



Mucin and soluble extractives 0.14 1.53 



Total ash 0.88 2.72 



Total P 2 O 5 0.20 i.oo 



These concretions frequently give rise to serious pathologi- 

 cal conditions and they must then be removed by surgical oper- 

 ations. In addition to the above constituents the stones con- 



