THE BILE. 205 



finally, Kolliker has found that the capillary bile ducts in the liver of 

 the rabbit may become visible in their usual positions in thin sections 

 hardened in alcohol, where no injection has been practised. They are, 

 therefore, to be regarded as the finest commencing ramifications of the 

 biliary canals, which receive the secreted fluids directly from the sub- 

 stance of the glandular cells. 



Physical and Chemical Characters of the Bile. The bile is distin- 

 guished from all the other secretions discharged into the alimentary 

 canal principally by the fact that it does not contain any albuminous 

 ingredient analogous to those of the saliva, the gastric, pancreatic, or 

 intestinal juices ; its most important constituents being nitrogenous 

 crystallizable substances, together with cholesterine and coloring mat- 

 ters. Bile taken from the gall-bladder contains, it is true, a certain 

 amount of mucus, which gives it more or less of a ropy and viscid charac- 

 ter; but this mucus is secreted by the gall-bladder itself, and bile taken 

 from the gall-ducts in the substance of the organ is always perfectly 

 fluid and watery in consistency. Furthermore, the gall-bladder is by 

 no means constantly present, even in the higher animals, being absent, 

 according to Wagner, in the horse, the camel, most of the pach^dermata 

 and several of the gnawing animals, and at the same time present in 

 many closely allied species. The bile accordingly, in its essential in- 

 gredients, differs in a marked degree from the digestive secretions 

 proper. 



The bile, as it comes from the gall-bladder, is a clear, more or less 

 tenacious and ropy fluid, neutral in reaction, with a faint and rather 

 indefinite animal odor. If it be shaken up with air, or if air be blown 

 into it through a narrow tube, it easily foams up into a frothy mixture 

 which remains for a long time on the surface of the fluid. This property 

 of frothing upon agitation with air does not depend upon the mucus which 

 it contains, but upon the biliary salts proper, namely, the sodium glyco- 

 cholate and taurocholate ; since these salts iu a pure watery solution 

 exhibit the same property. 



Its specific gravity is rather high, as compared with that of the other 

 secretions. In ox-bile, we have found it to be 1024, in pig's bile 1030 

 to 1036. The specific gravity of human bile, according to Robin, is 

 from 1020 to 1026 ; according to Jacobsen, in bile from a biliary fistula, 

 but little over 1010. We have found it, in bile taken from the gall- 

 bladder, 1018. 



Its color varies, in different species of animals, from a reddish-orange 

 to a nearly pure green, and in different instances presents all the inter- 

 mediate tints of golden-yellow, reddish-brown, olive-brown, olive, yel- 

 lowish-green, and bronze-green. It may be described in general terms as 

 a greenish-bronze, with sometimes more or less of an orange tint. 

 Human bile from a biliary fistula was found by Jacobsen to be of a 

 clear yellowish bronze-green; that taken from the gall-bladder after 

 death is usually of a dark golden-brown. Dog's bile is of a brownish- 

 olive or bronze color; pig's bile of a reddish-orange or reddish-brown; 



