524 Drs. P. T. Herring and S. Simpson. [May 1, 



variations thus brought about point to a mechanical explanation of their 

 occurrence. Heidenhain argued that bile absorption took place with greater 

 rapidity at a low blood pressure, while the rate of secretion by the liver 

 cells was also diminished. No doubt this is a potent factor in the long 

 run, yet the slight and rapid changes in pressure that occur must be 

 mechanical. Stimulation of the vagus nerve, for instance, causes a rapid and 

 simultaneous fall of both bile pressure and portal vein pressure. In Dog C, 

 with bile pressure 204 mm., and portal vein pressure 107 mm., stimulation 

 of left vagus by faradic current for five seconds caused an immediate fall of 

 bile pressure to 195 mm. and blood pressure to 95 mm. One minute later 

 bile pressure had risen to 214 mm. and blood pressure to 115 mm. 



Injection of extract of duodenal mucous membrane into a vein frequently 

 caused a rise of bile pressure, and was found to increase the rate of secretion 

 at zero pressure. It was not always successful, and often, while found to be 

 very active on pancreatic secretion, had no effect on bile secretion or 

 pressure. 



The injection of bile into a vein was invariably attended by increased rate 

 of secretion. It usually brings about an increase of bile pressure ; but if the 

 latter is high at the time of injection very little effect is noticed. 



The animals we experimented on were, with a few exceptions, well 

 nourished, and had been fed in the morning some hours before being 

 anaesthetised. The rate of bile flow as determined before estimation of bile 

 pressure was found to be very variable. A rapid rate of secretion is not 

 essential to the production of a high pressure, but it influences the form of 

 the pressure curve. The size and weight of the animal does not appear to 

 influence bile pressure, provided the animals are of the same species. 



We did not take many subsequent records of bile pressure in the same 

 animal. The rate of secretion of bile is usually diminished after the bile 

 duct has been obstructed for some time, but not invariably; we have 

 obtained records of bile flow in which the rate has been increased. 

 Subsequent records of bile pressure give as a rule lower readings than the 

 first, as was pointed out by Friedlander and Barisch. An exception may be 

 quoted. In dog D a maximum pressure of bile of 285 mm. was recorded. 

 After release of the bile from the bile duct a record of bile flow was taken, 

 and, half an hour later, secretion was more rapid -than it had been prior to the 

 first experiment. A second record of bile pressure, taken an hour after the 

 first, reached a maximum of 305 mm. bile, an increase of 20 mm. pressure. 

 A lower second reading is not therefore essential, and with an increased rate 

 of secretion by the liver cells there may be, as in this case, a higher pressure 

 reached. 



