Chap, xii.] OF DIGESTION. 189 



phosphates, chlorates, organic salts of soda, cholesterine, and so 

 on. It is alkaline, but only during digestion. In addition, we 

 do not find in bile any albuminoidal substance ' and it does not 

 coagulate through heat, the acids, the metallic salts. 



We have seen that the liver of the superior mammifers is 

 formed by the assemblage of two apparatus, the one glycogenical, 

 the other biliary. The first acts at the expense of the venous 

 blood, charged with nutriments brought to it by the vena portse, 

 that is to say, the common trunk of the intestinal veins. The 

 secretory organ of the bile, on the contrary, elaborates its secre- 

 tion at the expense of the general arterial blood, and we stop 

 the biliary secretion by binding the hepatic artery. The same 

 thing, moreover, takes place by absolute necessity in the inferior 

 animals whose liver is not in contact with any vena portse. 

 Poured on the aliments the bUe seems to act on the fat bodies 

 which it emulsionises, and also on the albuminoidal matters im- 

 pregnated with gastric juice. It neutralises them first of all, 

 then stimulates their dissolution. But it seems to acquire all its 

 properties only after blending with another liquid, the pancreatic 

 juice. 



Does the pancreas exist in the invertebrates ? This is a ques- 

 tion of comparative physiology which still waits for a reply. 

 We have seen that we do not begin clearly to recognise the 

 pancreas except in fishes, and then only in a rudimentary state. 

 In the superior vertebrates, it is a large gland cluster-like, 

 pouring an abundant liquid into the intestine through a conduit 

 which sometimes anastomoses with the biliary or choledochal 

 canal, and sometimes opens direct into the intestine, generally 

 in immediate proximity to the biliary conduit, sometimes at a 

 considerable distance from that conduit and below it. The 

 pancreas secretes a colourless limpid, viscous and alkaline liquid. 

 This liquid contains a special albuminoidal substance called 

 'pancreatine, and this substance is in such quantity there, that 

 through heat or alcohol the pancreatic juice coagulates in mass 

 1 Oh. Kobin, Lemons sv/r Us Rv/mewrs, p. 501. 



