INFLUENCE OF VARIOUS FACTORS. 567 



which has to deal with nitrogen in excess of the requirements of the 

 body. 



After every kind of food the absorption of bile salts and their action 

 on the liver must be taken into account as a factor in increasing the 

 now of bile (see p. 563). 



Influence of pressure of surrounding structures. The liver, 

 being situated just below the diaphragm and above the abdominal 

 viscera, is subject to marked variations in pressure. It has already 

 been pointed out that a considerable quantity of bile may collect in 

 the bile passages. By pressure from adjacent organs, this may be 

 squeezed out. The facts that section of one vagus reduces the bile flow 

 only when the frequency of respiration is diminished, 1 and that section 

 of the vagus just above the diaphragm, which has no influence on -the 

 rate of respiration, leaves the bile secretion unaltered, and that stimula- 

 tion has also no effect, seem to indicate that the flow of bile is acceler- 

 ated by respiratory movements. 



The very marked rise in the amount of bile poured out between four 

 and eight A.M. in a case of biliary fistula, 2 just at the time when the 

 patient wakened and commenced to move about, further supports the 

 view that pressure on the liver may cause an increased flow of bile. 



Direct influence of nerves upon bile secretion. It has already 

 been pointed out that the secretion of bile may be indirectly modified 

 by the influence of nerves upon the blood vessels. The flow of bile may 

 also be increased through the stimulation of the nerves to the muscular 

 coat of the bile ducts and gall bladder. Eeflex stimulation through 

 these nerves probably accounts for the first gush of bile after food is 

 taken. There is, however, no evidence that stimulation of nerves can 

 directly increase or diminish the actual secretion of bile any change 

 in the flow being fully explained by indirect action. The facts that 

 the injection of pilocarpine, which so markedly increases the flow of 

 saliva and of pancreatic juice, has no influence on bile secretion, 3 and 

 that atropine has no action in arresting the secretion, 4 seem to oppose 

 the idea that there is any direct nervous influence upon the process. 



Influence of various chemical substances on bile secretion. 

 Certain substances, when introduced into the portal blood, either directly 

 or through the alimentary canal, cause an increase in the secretion of bile. 



Tarchanoff 5 found that when haemoglobin is injected into the blood- 

 vessels the bilirubin of the bile is increased in amount. Stadelman 6 and 

 Afanassiew 7 afterwards demonstrated that such drugs as toluylenediamin 

 and arseniuretted hydrogen, which cause the solution of haemoglobin 

 from the blood corpuscles, produce not only an increase in the bilirubin 

 of bile, but also an increased flow of bile, and that this polycholia seems 

 to be proportionate to the destruction of haemoglobin. It is therefore 

 clear that the passage of free haemoglobin to the liver acts as a stimulant, 

 and may produce an increased flow of bile ; and hence all substances 

 which bring about an escape of the blood colouring-matter tend to 

 increase the secretion of bile. 



1 Hermann's "Handbuch," S. 270. 



- Rep. Lai). Roy. Coll. Phyx., Edinburgh, vol. iii. p. 200. 



3 Paschkis, Med. Jdhrb., Wien, 1884, S. 169. 



4 Rutherford, "Action of Drugs on the Secretion of Bile," Edinburgh, 1880, p. 96. 



5 Arcli.f. d, ges. PhysioL, Bonn, 1874, Bd. ix. 



Arch. f. exper. Path. u. PharmakoL, Leipzig, 1883, Bd. xcviii. S. 460. 

 7 VircJiows Archiv, 1884, Bd. xcviii. S. 460. 



