320 SECRETION OF BILE. 



The influence of the food is most striking. The most abundant secre- 

 tion takes place after free ingestion of meat ; on addition of fat or carbo- 

 hydrates scarcely any more is formed. In a state of hunger the quantity 

 is reduced from one-third to one-half, and even more with a pure fat-diet. 

 The ingestion of water increases the amount, with simultaneous relative 

 reduction in the solid constituents. 



The influence of the circulation. The portal vein furnishes especially 

 the material for the production of the bile, and in greater degree than the 

 hepatic artery. The latter is at the same time the nutrient vessel of 

 the tissues of the liver. This is shown by the following observations : 



(a) Simultaneous ligation of the hepatic artery (diameter, 5^ mm.) and of 

 the portal vein (diameter, 16 mm.) abolishes the secretion of bile. 



(b) If the hepatic artery is ligated, the portal vein alone maintains the secre- 

 tion. According to Kottmeier, Betz, Cohnheim and Litten, ligation of the artery 

 or of one of its branches is said, further, to result in necrosis of the parts supplied, 

 and possibly of the entire liver, as the artery is the nutrient vessel of this organ. 

 After ligation of the artery the production of urea diminishes greatly; while 

 after ligation of the portal vein this is said to remain almost normal. 



(c) If the branch of the portal vein for a lobule of the liver is ligated, only 

 slight secretion takes place in this lobule through the agency of the artery. 



Thus neither exclusive ligation of the hepatic artery nor exclusive gradual 

 obliteration of the portal vein (rarely observed as a morbid condition) results in 

 cessation of the secretion. Only diminution in the secretion takes place. The 

 observation that the secretion ceases after sudden ligation of the portal vein 

 (which, besides, is rapidly fatal) is to be explained by the fact that, in addition 

 to the diminution in the secretion, the enormous blood-stasis in the abdominal 

 viscera after this operation makes the liver intensely anemic and therefore unsuited 

 for secretion. 



(d) If the blood of the hepatic artery is introduced directly into the lumen 

 of the opened portal vein, ligated peripherally, the secretion continues. 



(e) The passage as rapidly as possible of large amounts of blood through 

 the liver acts most favorably upon the secretion. In this connection the pre- 

 vailing blood-pressure is not of primary importance, for after ligation of the in- 

 ferior cava above the diaphragm, in consequence of which the highest degree of 

 blood-pressure due to stasis develops, the secretion ceases. The transfusion of 

 considerable quantities of blood always increases the production of bile, although 

 excessive pressure in the portal vein, from the introduction of blood from the 

 carotid artery of another animal restricts the production. 



(f) Profuse loss of blood has a tendency to cause cessation of bile-production 

 before the function of the muscular and nervous apparatus is abolished. A more 

 abundant blood-supply to other organs, as, for example, to the muscles of the 

 body engaged in hard labor, diminishes the secretion. 



(g) The influence of the nerves. All procedures that cause contraction of 

 the arteries of the abdomen, such as irritation of the valve of Vieussens, of the 

 inferior cervical ganglion, the hepatic nerves the splanchnic nerve, the spinal 

 cord, whether directly, as by strychnin, or reflexly, by irritation of the sensory 

 nerves, diminish the secretion. All procedures that induce stagnation of blood in the 

 hepatic vessels, such as division of the splanchnic nerves, diabetic puncture, divi- 

 sion of the cervical cord, have a like effect. Paralysis (ligation) of the hepatic 

 nerves is said at first to increase the secretion of bile, with reddening of the liver. 



(h) With regard to the raw material brought to the liver by the blood-vessels 

 for the production of bile, the difference in the composition of the blood in the 

 hepatic veins and that in the portal vein is noteworthy. The blood in the hepatic 

 veins contains somewhat more sugar, lecithin, cholesterin, and blood-corpuscles, 

 but, on the contrary, it is deficient in albumin, fibrin, hemoglobin, fat, water and 

 salts. The liver is capable of excreting unchanged in the bile biliary pigments 

 circulating in the blood. 



The production of bile is dependent preeminently upon the trans- 

 formation of the red blood-corpuscles, as they furnish the material for 

 the formation of some of the constituents. 



