I IO THE PHYSIOLOGY OF DIGESTION AND ABSORPTION 



fibrous. A little plain muscular tissue may exist. Its capac- 

 ity is about one and a half ounces. Mucous glands are found 

 in its lining, as in that of the large ducts, and these are re- 

 sponsible for the mucin of the bile. 



Hepatic Nerves. With regard to the exact destination of 

 the nerves entering the liver, little is known. Evidence going 

 to establish the termination of fibers in the cells, that is, the 

 existence of distinct secretory fibers is meager. There is 

 little doubt that secretory fibers for the glycogenic func- 

 tion of the liver do exist. It is known that fibers from the 

 vagus, phrenic and solar plexus enter the fissure, but they 

 cannot be followed farther than the ramifications of Glisson's 

 capsule between the lobules. Of course, vaso-motor fibers 

 go to the vessels, as elsewhere. Fibers acting similarly go 

 also to the muscular tissue of the large ducts and of the gall 

 bladder. The contraction of the gall bladder is thought to be 

 reflex, afferent impressions being conveyed by the vagus 

 from the mucous membrane of the duodenum. 



Hepatic Lymphatics. The lymphatics are abundant, and 

 those not originating in the connective tissue are thought to 

 originate by perivascular canals surrounding the blood-ves- 

 sels of the lobules. The fact that when the outflow of bile is 

 occluded it passes, not into the vascular, but into the lym- 

 phatic circulation is a curious circumstance. It may be due 

 to the absence of a definite wall for the intralobular ducts 

 and their comparatively free communication with the lym- 

 phatics in those localities. 



Properties and Composition of Bile. Human bile is of a 

 dark greenish-red color, has a bitter taste and is practically 

 odorless when fresh. It undergoes putrefaction easily, but 

 is not coagulable by heat. It is viscid, chiefly on account of 

 the mucin it contains. It has an alkaline reaction, and a spe- 

 cific gravity of about 1030. Besides water, which consti- 

 tutes more than ninety per cent, of its bulk, it contains the 

 sodium salts of taurocholic acid and glycocholic acid (the 

 biliary salts), cholesterin, bilirubin, lecithin, fats, soaps, mu- 



