194 



Scientific Proceedings (68). 



the thorax. By the degree of tension exerted on this thread, the 

 amount of blood passing from the veins to the arterial side of the 

 circulation could be accurately controlled and, inconsequence, the 

 blood pressure. 



It was found that a two-hour period of reduction of the arterial 

 blood pressure to from 30 to 40 mm. of Hg was, with few excep- 

 tions, fatal within the next eighteen hours, even though there 

 might be a rise of arterial blood pressure to nearly the normal 

 height for a period of three to four hours after the release of the 

 ligature around the inferior vena cava. Manometric tracings of 

 the systemic and the portal venous pressures showed an immediate 

 rise in the venous blood pressure within these veins, following the 

 occlusion of the inferior vena cava. As the experiment con- 

 tinued, there was a gradual fall in the pressures. 



Volumetric tracings of the intestinal loops showed regularly 

 a fall in the volume of the intestines during the period of occlusion. 

 In the majority of the experiments, for a short time during the 

 beginning of the period of occlusion there was a rise in the volume 

 of the intestines. This was succeeded by a steady fall, which was 

 maintained until a terminal stage when a very extreme condition 

 of shock was reached, in which the volume of the intestine would 

 show a small terminal increase. 



Volumetric tracings of the liver, however, showed a consistent 

 increase in the volume of this organ to a late stage in shock. The 

 volume of the liver showed an increase relative to that of the 

 intestines. It would decrease in size at the time of the terminal 

 increase in volume of the intestines; and we attributed the 

 terminal increase in volume of the intestines as being due simply 

 to a draining away of the blood sequestrated in the liver by tissues 

 in the intestines absolutely devoid of tone. 



During the period when the progressive fall in the volume of 

 the intestines is well instituted, the volume of the intestines and 

 also of the liver shows a marked dependence upon the arterial 

 blood pressure; whereas in the normal animal at the start of the 

 experiment a tightening of the ligature around the inferior vena 

 cava and the production of a rise in this manner of the portal 

 venous pressure caused an increase also in the volume of the 

 intestines. Later in the experiment, a similarly produced increase 



