316 COLOURING MATTERS. 



times find ramifying nodular concretions in the gall-bladder and in 

 the biliary ducts, consisting almost entirely of bile-pigment. This 

 pigment is found, not only in the bile of man and of the ox, but 

 also in that of other carnivorous and herbivorous animals; it 

 presents, however, the most varied modifications, as we find from 

 the difference of colour exhibited by the bile not only of different 

 genera but even of different individuals of tbe same species ; thus, 

 the bile of a dog is of a yellowish brown tint, that of the ox is 

 brownish green, while that of birds, fishes, and amphibia is usually 

 of an emerald green. 



The bile-pigment which mixes with the contents of the 

 intestines becomes very rapidly modified, and ceases to present the 

 ordinary reaction with nitric acid ; the change which it here very 

 rapidly undergoes, appears to be the same which we can induce 

 artificially by nitric acid. It is in this form that it occurs in the 

 solid excrements, unless when diarrhrea is present, in which case 

 unchanged pigment is found in the alvine dejections. It is only 

 rarely that the excrements assume a green tint from the green 

 modification of the pigment ; the green coloration more frequently 

 depending on an admixture of partially decomposed blood. Bile- 

 pigment is never entirely absent in the excrements except in the 

 rare cases of icterus, which are accompanied with a complete 

 stoppage of the biliary secretion. 



Bile-pigment occurs in the blood and in serous fluids in all 

 forms of icterus ; sometimes however it is absent, or at all events, 

 cannot be detected in the blood in certain forms of inflammation, 

 while cholic acid or its conjugated acids may be recognised ; the 

 converse case, namely, the presence of bile-pigment and the absence 

 of cholic acid in the blood is, however, more frequently observed. 

 We shall return to this subject in the second volume. 



In diseases the bile-pigment is especially deposited in the fluids 

 of the cellular tissue, in the aqueous humour, the vitreous humour, 

 the crystalline lens, and above all in the sclerotic ; cases have even 

 occurred in which the saliva and the sweat have been coloured 

 yellow ; sometimes the organism may so long endure this impure 

 condition of the blood, that the pigment saturates even the car- 

 tilages, ligaments, and bones,* and may actually be recognised in the 

 nerves. 



Schererf often discovered decided traces of bile-pigment in the 

 urine of healthy persons, especially during the hot months. In 



* Kerkring, Spicil. anat. obs. 57, p. 118. 



t Ann. d. Ch. u. Pharm. Bd. 57, S. 181- IU5. 



