The Liver and Pancreas. 165 



encloses the proteids, which putrefy, hence the odour. The 

 bile, he states, is not an antiseptic, but acts as a natural 

 purgative and keeps up intestinal peristalsis, and by so 

 doing hurries the food out of the system before it undergoes 

 putrid decomposition. 



Some of the constituents of the bile are broken up in 

 the bowel : for instance, the bile acids yield cholalic acid, 

 setting free glycin and taurin. The latter, being absorbed 

 again are carried to the liver, and may probably there 

 excite the further secretion of bile acids ; cholalic acid is 

 excreted with the faeces. In the bowels the pigments also 

 undergo change, yielding stercobilin (the colouring matter 

 of the fgeces) and urobilin (the colouring substance of the 

 urine). 



Glycogen. 



It is quite certain that the largest gland in the body 

 must have some other function than that of the secretion 

 of a fluid of comparatively unimportant digestive power, 

 and such is the case. The liver manufactures and stores 

 up in its cells a peculiar substance known as Glycogen, or 

 animal starch. 



The literature of glycogen is extensive ; perhaps no sub- 

 stance has given rise to greater controversy. All we can 

 attempt here is to give a general and brief outline of a 

 complicated subject on which much diversity of opinion 

 has existed. 



The sugar in the food, or that derived from starch -con- 

 version, finds its way by means of the intestinal blood- 

 vessels into the portal vein ; from here it passes into the 

 liver. Under ordinary circumstances it is stored up in the 

 liver as glycogen, being, in fact, reconverted into a kind 

 of animal starch, and it is gradually doled out to the 

 system as sugar as the body is in need of it. 



The liver regulates the amount of sugar which should 

 pass into the blood ; so much and no more is admitted to 

 the circulating fluid, the amount varying between "05 and 

 '15 per cent. The sugar in the blood of the ox was esti- 

 mated by C. Bernard at -17 per cent. ; in the calf, 1 per 



