370 THE HUMAN BODY. 



maltose ; dissolves proteids (if necessary) and converts them 

 into peptones; emulsifies fats, and, to a certain extent, breaks 

 them up into glycerin and fatty acids; the latter are then 

 saponified by the alkalies present. 



The Bile. Human bile when quite fresh is a golden 

 brown liquid; it becomes green when kept. As formed in 

 the liver it contains hardly any mucin, but if it make any 

 stay in the gall-bladder it acquires much from the lining mem- 

 brane of that bag, and becomes slimy and " ropy." It is 

 alkaline in reaction and, besides coloring matters (the more 

 important of which, bilirubin, is probably a waste product 

 derived from haemoglobin), contains mineral salts and water, 

 and the sodium salts of two nitrogenized acids, taurocliolic 

 and glycliocholic, the former predominating in human bile. 



Pettenkofer's Bile Test. If a small fragment of cane 

 sugar be added to some bile, and then a large quantity of strong, 

 sulphuric acid, a brilliant purple color is developed, by cer- 

 tain products of the decomposition of the bile acids; the 

 physician can by this test, in disease, detect their presence in 

 the urine or other secretions of the Body. Gmetin's Bile 

 Test. Whe bile-coloring matters, treated with yellow nitric 

 acid, go through a series of oxidations, accompanied with 

 changes of color from yellow-brown to green, then to blue/ 

 violet, purple, red, and dirty yellow. 



Bile has no digestive action upon starch or proteids./ji It 

 does not break up fats, but to a limited extent emulsifies 

 them, though far less perfectly than the pancreatic secretion. 

 It is even doubtful whether this action is exerted in the in- 

 testines at all. In many animals, as in man, the bile and 

 pancreatic ducts open together into the duodenum, so that, 

 on killing a dog during digestion and finding emulsified fats 

 in the chyle, it is impossible to say whether or no the bile 

 had a share in the process. In the rabbit, however, the pan- 

 creatic duct opens into the intestine about a foot farther 

 from the stomach than the bile-duct, and it is found that if a 

 rabbit be killed after being fed with oil, no milky chyle is 

 found down to the point where the pancreatic duct opens. 

 In this animal, therefore, the bile alone does not emulsify 

 fats, and, since the bile is pretty much the same in it and 

 other mammals, it probably does not emulsify fats in them 

 either. From the inertness of bile with respect to most food- 

 stuffs it has been doubted whether it be of any digestive use at 



