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



being the greatest. The average maximum for cats, 304*4 mm., in our series 

 corresponds closely with the average maximum for dogs, 300 mm. Eabbits 

 have a lower pressure, in round numbers about 200 mm. bile. In a healthy 

 monkey tjie maximum pressure was 321 mm. Bile pressure in the monkey 

 probably averages about the same as that in the cat and dog. 



In all bur experiments the pressures recorded are measurements of the 

 pressure in the common bile duct in terms of a vertical column of bile. 

 The gall bladder was occluded in every case, so that its contractions could 

 have no influence on the pressure ; that the occlusion was complete was 

 verified in every animal after death. The free opening of the abdomen 

 under warm normal saline prevented extraneous pressure on the liver by 

 abdominal and diaphragmatic movements ; consequently, little oscillation of 

 the column of bile ever occurred, and the readings may be accepted as 

 indicating a true secretion pressure. 



Graphic representations of the rise of bile pressure and its time relations 

 are interesting. The accompanying chart gives several examples of pressure 

 curves. In it the figures on the left-hand side denote the pressure in 

 terms of millimetres of bile, while the figures below the chart represent time 

 in five-minute intervals. 



As a general rule, the bile pressure rises rapidly at first, the rate 

 depending chiefly on the rate of bile secretion. After reaching a pressure 

 of 100 mm. or thereabouts, the rise of pressure begins to slow down. 

 Cat A, Dog E, and Eabbit D (see chart) gave typical pressure curves. In 

 these animals the bile pressure rose rapidly, but the amount of rise 

 diminished at every reading until a maximum was reached, after which the 

 pressure began to fall. The curve of pressure in Cat P represents another 

 type in which, after attaining a certain height, the pressure remains 

 stationary or even falls, but only temporarily, afterwards rising gradually, 

 but slowly. In this cat the maximum pressure, 315 mm., was attained 

 3 hours 55 minutes after commencement of the experiment. We had several 

 examples of this slow rise to a maximum. In the chart is also placed a 

 short record of the height of portal vein pressure of Cat P ; the large drop 

 in bile pressure was due to interference with the portal circulation in 

 putting the cannula into the splenic vein; some of the sodium carbonate 

 solution also entered the circulation. A short record of portal vein pressure 

 in Dog E is also given. A simultaneous reading of bile pressure and portal 

 vein pressure shows that the two coincide in their variations. Eise of 

 blood pressure is accompanied by a rise of bile pressure; fall of blood 

 pressure by a fall of bile pressure. Changes in blood pressure in the portal 

 vein at once show themselves in the rise or fall of bile pressure. The rapid 



