ITS CONSTITUENTS. 63 



phosphate of lime and magnesia, and extremely minute quantities 

 of iron and manganese, but no alkaline sulphates. No salts of 

 ammonia are found in fresh healthy bile. The relation of the 

 potash and soda in the bile of different animals a fact noticed 

 by Bensch, but more prominently evolved by Strecker is 

 deserving of careful attention : the bile of salt-water fishes con- 

 tains almost exclusively potash-salts, while that of the herbivorous 

 mammalia contains almost exclusively soda-salts; whereas from 

 the nature of the food of the animals, we should have expected to 

 have met vvith the opposite result. We have already alluded to the 

 presence of copper in the bile. (See vol. I, p. 451.) 



Finally, a greater or lesser quantity of mucus always occurs in 

 the bile. This, like other varieties of mucus, is mixed with 

 numbers of epithelial cells ; here, however, the mucus-juice very 

 much preponderates over the epithelium. 



Fresh normal bile contains no morphological elements except 

 the cells of cylindrical epithelium thrown off from the mucous 

 membrane of the biliary ducts and the gall-bladder; these cells 

 often remain grouped together in their natural arrangement. 



It is needless to introduce in this place any historical sketch 

 of the manifold experiments and views which have been adduced 

 in reference to the composition of the bile, since they are described 

 with more or less minuteness in all our text-books of Animal 

 Chemistry, and in every monograph on the bile, and since they 

 do not throw the slightest light on the complex nature of this 

 fluid and of its constituents. In reference to the writings of 

 Berzelius, it seems, however, necessary to state, that according 

 to his view, which has very recently been defended by Mulder, the 

 most essential constituent of the bile is not an acid in combina- 

 tion with soda, but an indifferent substance named bilin> which in 

 its decomposition gives rise to those substances which were 

 formerly described by Gmelin, and subsequently by Dema^ay 

 and others, as occurring in the bile. Any one who carefully 

 studies the chemical characters of taurocholic acid (the choleic 

 acid of Strecker), and compares them with those which are 

 ascribed by Berzelius to his bilin, will readily detect the causes 

 of the error by which that chemist was led to assume the exist- 

 ence of an indifferent bilin ; and they will no longer wonder that all 

 who have repeated the positive experiments of Berzelius have 

 quite as thoroughly confirmed them, as those which were insti- 

 tuted by Liebig and his pupils, but led them to a different view of 

 the subject. 



