THE HEPATIC CIRCULATION. 161 



wall is freely opened, and a loop of intestine ligatured at either end, and, 

 separated from the remaining guts, is allowed to hang down into a glass vessel 

 partly tilled with warm saline. At the orifice of the glass vessel the mesentery 

 is surrounded by a broad band of thin indiarubber, which is kept sufficiently 

 tight by means of a clip. By this means the chamber is rendered air-tight, and 

 yet the mesenteric vessels are not over-compressed. From the top of the chamber 

 a tube passes to a sensitive tambour. Bunch has also worked at the innervation 

 of the intestinal vessels, using Schafer's visceral plethysmograph (Fig. 99). l 



Hallion and Francois-Franck 2 applied plethysmography to other abdominal 

 organs, and took simultaneous tracings of the volume of the kidney, intestine, 

 and spleen, together with the arterial blood pressure (see Fig. 97). 



They found that excitation of the central end of the sciatic nerve 

 produces reflex vaso-constriction in the small intestine, the spleen, the 

 liver, and the kidney, and vaso-dilatation of the colon, and that excita- 

 tion of the peripheral end of the vagus in the atropinised animal (i.e. 

 cardio-inhibitory fibres paralysed) produces marked vaso-dilatation in the 

 intestines. 3 



The vaso-constrictor fibres issue from the fifth thoracic nerve 

 downwards. The upper roots supply the duodenum and jejunum, the 

 lower roots the ileum and colon. On exciting the eleventh, twelfth, 

 and thirteenth thoracic, and first and second lumbar roots, marked vaso- 

 dilatation follows, after a fugitive preliminary constriction. This vaso- 

 dilatation is accompanied by a fall of arterial pressure. The usual effect 

 on exciting the splanchnic nerves is a great rise of arterial pressure, 

 followed by a fall. This double effect is due to the presence of both 

 vaso-constrictors and dilators in these nerves. The vaso-constrictors 

 are exhausted before the vaso-dilators. 



The Hepatic Circulation. 



By simultaneous records of aortic and portal pressures, Bayliss and 

 Starling i determined that the constrictor fibres to the branches of the 

 portal vein issue by the anterior roots from the third to the eleventh 

 thoracic nerves. Cavazzani and Manca 5 attempted to investigate the 

 innervation of the hepatic blood vessels by artificially circulating warm 

 normal saline solution through the organ, and measuring the output 

 from the vena cava inferior. They ascribe both constrictor and dilator 

 fibres to the splanchnic nerves, and dilator fibres to the vagus. 



Francois-Franck and Hallion have investigated the hepatic circula- 

 tion by the plethysmographic method. On excitation of the central 

 end of the sciatic nerve, the liver vessels are constricted. The pressure 

 in the portal vein rises slightly, in spite of the concomitant contraction 

 of the mesenteric vessels. On exciting the central end of the vagus, 

 either contraction or dilatation follow. By stimulation of the 

 thoracic sympathetic cord, blood was actively expelled from the liver. 

 If the hepatic nerves were divided, this stimulation of the sympathetic, 

 by causing contraction of the spleen, produced dilatation of the liver. 

 Nicotine, when injected into the hepatic circulation, contracted the 



1 "Proc. Phys. Soc," Journ. Physiol., Cambridge and London, March 1898. 



2 Arch, de physiol. norm, etpath., Paris, 1896, p. 502. 



3 Bunch was unable to obtain an effect upon the intestinal vessels on stimulating the 

 peripheral vagus after atropine. 



4 Journ. Physiol., Cambridge and London, 1894, vol. xvii. p. 120. 



5 Arch. ital. de biol., Turin, 1895, vol. xxiv. pp. 33, 295. 



vol.. II. — II 



