250 THE LIVER. 



readily because the contact of fat and membrane is closer than 

 it otherwise would be, is abandoned. This theory was based on 

 the reputed facts that oil would rise higher in a capillary tube 

 which had been moistened with bile than in one which had been 

 moistened with water, and that a filtering medium wet with bile 

 would permit oil to pass through more readily than one wet with 

 water. Experiment, however, demonstrates that these are not facts. 

 In view of the present belief that absorption depends not upon 

 osmosis, but upon the activity of lining epithelium, it is not 

 improbable that the cells covering the mucous membrane of the 

 intestine are stimulated by the bile-acids to increased absorption 

 of fat. 



The antiseptic property of bile is very small ; still, when bile 

 is not permitted to enter the intestine putrefaction of the intestinal 

 contents takes place more readily than is normal. The explana- 

 tion of this is not satisfactory. 



Another purpose which bile subserves is to precipitate the pro- 

 teids of the chyme which are not peptonized, or only partially 

 so, as, for instance, syntonin, as that mixture comes into the intes- 

 tine from the stomach. With this precipitated matter is also some 

 muciu from the bile. The result of this precipitation is a tenacious 

 mass which adheres to the intestinal wall, and which is therefore 

 longer exposed to the action of the digestive fluids of the intestine, 

 and, therefore, more perfectly digested than it otherwise would be. 



Innervation. So far as the formation of bile is concerned, 

 the liver-cells do not-appear to be supplied with secretory nerves. 

 There is great difficulty in determining this question with cer- 

 tainty, for the reason that in stimulating the nerves to the liver 

 vasomotor fibers are stimulated, and this, of course, affects the 

 blood-supply to the organ, so that it is impossible to say whether 

 what occurs is the result of stimulating secretory nerves or of an 

 increased supply of blood. There is no doubt, however, that it 

 is to the blood of the portal vein that the secretion of bile must 

 be ascribed, and that when this supply is increased the bile secre- 

 tion will be correspondingly augmented. This occurs during 

 digestion, and it is, therefore, at this time that the amount of bile 

 is increased. 



It is probable that the muscular tissue of the gall-bladder and 

 bile-ducts is supplied with nerves, so that when the mucous mem- 

 brane of the stomach or intestine is stimulated afferent impulses 

 reach a nerve-center through the vagus, and efferent impulses pass 

 out and are carried to this muscular tissue through the splanchnics ; 

 the action is, in other words, reflex. 



Movements of the Small Intestine. When the food 

 enters the small intestine through the relaxed sphincter pylori, 

 the free hydrochloric acid present brings about, by contact with 

 the duodenal mucous membrane through reflex action, a closure 

 of the pyloric sphincter, and thus the quantity of food material 



