BILE OF ANIMALS. 25 



natrix is described by Gmelin as of a grass-green colour, trans- 

 parent, perfectly fluid, and passing through the ordinary change 

 of colour (blue, red, and yellow) on the addition of nitric acid. 



The bile of the Rana esculenta and R. temporaria is very fluid, 

 of a pale green colour, and yields the ordinary series of tests with 

 nitric acid. The bile of the water-frog leaves a somewhat 

 crystalline residue on evaporation ; the bile of the grass-frog 

 has a sweetish taste, and is less bitter than fish-bile. 



The bile of the Cyprinus leuciscus is described by Gmelin as 

 green, transparent, and fluid, communicating a sweet and after- 

 wards a very bitter taste to the gustatory organs, neutral in its 

 reaction, affected, as to its colour, by nitric acid like other bile, 

 and coagulating immediately on the addition of potash into a 

 greenish white granular mass, becoming covered, on evaporation, 

 with an almost colourless crystalline film, and yielding 14* 3 of 

 a dark green, transparent, crystalline residue. 



The bile of the Cyprinus bar bus is similar to that of C. leuciscus 

 in its physical characters, and yields 19'3 of a dark green 

 crystalline residue. 



The solid residue of the bile of the Salmofario and Esox Indus 

 is stated to be non-crystalline. 



On the Action of the Bile in the process of Digestion. 



We are as ignorant of the action of the bile on the che- 

 mical changes that the food undergoes in the intestinal canal 

 and in the process of chylification, as of the exact influence of 

 the saliva or of the pancreatic juice. Experiments, with the 

 view of deciding this point, have been instituted by Brodie and 

 by Tiedemann and Gmelin, and the conclusions to which they 

 lead are, that the bile does not exert any material influence upon 

 digestion and chylification. Assuming that these experiments 

 were correctly performed, the bile must be regarded as a mere 

 excretion, whose removal from the organism is as necessary for 

 the preservation of the normal constitution of the blood as the 

 removal of carbonic acid, urea, &c. 



Tiedemann and Gmelin state as the results of their observa- 

 tions on animals, in which the flow of bile into the intestine was 

 prevented : 1st, that digestion (as had been stated by Brodie) 

 proceeds just as perfectly as when the supply of bile is not 



