274 Dr. C. Bolton. Dropsy produced by [Dec. 19, 



precisely this collapse of the lung which induced Eanvier(5) to ligature the 

 vein in the abdomen, thinking that if dropsy were to be produced by venous 

 obstruction he should obtain it by this means ; however, in this case the 

 anastomoses are too readily established, and Eanvier fell into error in 

 thinking he had disproved Lower's results. 



Incomplete Occlusion. Diameter of Tube, 1J mm. — This practically amounts 

 to total occlusion of the vein, and death results with about 20 c.c. fluid in 

 the peritoneal cavity. 



Diameter of Tubes, 2 and 2^ mm. — Constrictions to both these diameters 

 may lead to death in a few hours, with 15 to 20 c.c. blood-stained fluid in the 

 peritoneal cavity ; on the other hand, the animal may survive the operation 

 and develop ascites, but for how long I have not determined. 



Diameter of Tube, 3 mm. — The animal survives, but if killed 24 hours after 

 the operation, 25 to 35 c.c. clear straw-coloured fluid will be found in the 

 peritoneal cavity, and possibly a few drops of fluid in the pleura?. One 

 animal lived four months, and at the autopsy showed no dropsy at all. 

 Anastomoses were well established in the abdominal wall, carrying the blood 

 to the superior vena cava. I have found ascites present 13 days after the 

 operation in one case. 



The fluid, therefore, is absorbed when the anastomoses are established. 

 The urine is diminished in amount when dropsy is being produced. 



Diameter of Tube, 4 mm. — A constriction to this amount does not lead to 

 ascites. 



The same general statement which was made with regard to constriction 

 of the superior vena cava may be made in the case of the inferior vena cava. 

 When the diameter of this vein is constricted to three-lifths of its normal 

 size, ascites appears, and when the anastomoses are completely established 

 this fluid disappears. If the vein is constricted below two-fifths of its 

 diameter, or if it is completely ligatured, death will result in a few hours, and 

 some ascitic fluid will be found in the peritoneal cavity. 



This statement, of course, applies to suddenly produced constrictions. 



(b) Upon the Circulation of the Blood. 

 Arterial Pressure. 

 A gradually increasing constriction of the inferior vena cava in the chest 

 is perfectly compensated for until a diameter of 3 mm. is reached, when the 

 arterial blood-pressure falls about 20 mm. Hg. Constrictions greater than 

 this produce proportionately greater depressions in the blood-pressure curve, 

 and complete ligature of the inferior vena cava causes the arterial pressure to 

 fall to 30 or 40 mm. Hg above zero. 



