INFLUENCE OF VARIOUS FACTORS. 565 



Further, the liver being placed upon the efferent vessel of the 

 alimentary canal, must have its vascular condition altered by every 

 modification in that of the gastro-intestinal tract, and it is impossible to 

 eliminate this element while studying the action of any agency on bile 

 secretion. 



Influence of the hepatic circulation upon bile secretion.- 

 The circulation in the liver may be profoundly altered without actual 

 stoppage of bile secretion. Thus it has been shown, in cases where, by 

 the method devised by Ore, the portal blood has been directed into the 

 inferior vena cava, that bile is still secreted by the liver ; l while 

 Wertheimer 2 has confirmed the results of older investigators, that 

 ligature of the hepatic artery does not immediately stop the secretion, 

 although ultimately necrosis of liver tissue supervenes and leads to 

 abolition of function. 



But while these marked disturbances do not at once stop secretion, 

 there is evidence that its rate depends upon the vascular supply. 

 Thus Heidenhain has shown 3 that in dogs, section of the splanchnic 

 nerves, which causes a dilatation of the portal vessels, produces a 

 marked increase in the now of bile. If, however, this local dilatation 

 is accompanied by a general dilatation, such as is produced by section of 

 the spinal cord in the neck, a fall in the secretion occurs. Munk, 4 on 

 the other hand, has shown that stimulation of the splanchnic nerves, 

 which produces constriction of the vessels, leads to a diminution in 

 the rate of bile secretion. 



How far this influence of alteration in the blood supply is due to 

 variation in pressure, and how far to alteration in the rate of blood flow 

 through the liver, has not been directly investigated. But the observa- 

 tion of Eohrig, 5 that constriction of the Vena cava inferior, which raises 

 the pressure in the liver while decreasing the rate of blood flow, 

 diminishes bile secretion, seems to indicate that the rate of flow is of 

 more importance than the mere intravascular pressure. In this con- 

 nection the relationship of the pressure of secretion to blood pressure 

 (p. 560) must be borne in mind. 



Effects of food. Starvation, according to Bidder and Schmidt, 

 causes a diminution in the amount of bile secretion, and a corresponding 

 fall in the amount of solids. 6 Their experiments are unsatisfactory, in 

 so far that cats were taken at various stages of starvation up to 240 

 hours after food, a temporary fistula made, and the bile secretion 

 determined for a short period only. The most recent contribution 

 to our knowledge of this subject was made by Lukjanow, 7 who 

 determined the changes in the various solids of the bile in guinea-pigs 

 kept without food or water. He concludes that both the secretion of 

 water and of solids diminishes throughout the period of fasting. 



From the investigations on the relationship of bile secretion to 

 the flow of blood through the liver, it is obvious that the dilatation 

 of the abdominal vessels, which occurs in digestion, will of itself 

 cause an increased secretion of bile. Such an increased flow has 



1 Arch. d. sc. bioL, St. Petersbourg, 1892, vol. ii. 



2 Arch, de physiol. norm, etpath., Paris, 1892, p. 577. 



3 Hermann's "Handbuch," Bd. v. S. 266. 



4 Arch. f. d. ges. Physiol. , Bonn, 1874, Bd. viii. S. 151. 



5 Med. Jahrb., Wien, 1873, Bd. ii. 



6 Bidder and Schmidt, " Die Verdauungssafte. " 



7 Ztschr.f. physiol. Chem., Strassburg, 1892, Bd. xvi. S. 87. 



