/. \ r FL UENCE OF VARIO US FA CTORS. 5 6 5 
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 gastrointestinal 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; 1 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 flow 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 Bohrig, 5 that constriction of the vena cava inferior, which raises 
the pressure in the liver wliile 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," 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. 
- Arch, dephysiol. norm, ctpath., Paris, 1892, p. 577. 
3 Hermanns "Handbucli," Bd. v. S. 266. 
4 Arch. f. d. ges. Physiol., Bonn, 1874, Bd. viii. S. 151. 
5 Med. Jahrh., Wien, 1873, Bd. ii. 
6 Bidder and Schmidt, " Die Verdauungssafte. " 
7 Ztschr. f. physiol. Chcm., Strassburg, 1892, Bd. xvi. S. 87. 
