Scientific Proceedings. 



57 



chcXtes ; while every mouse tumor that has been put through the 

 Levaditi method shows the presence of these organisms. 



Neither Lowenthal, nor Gaylord, nor I have claimed that these 

 spirochetes are the cause of mouse tumors, nor have we claimed 

 that spirochetes are the cause of human carcinoma. We have 

 always held to the parasite theory of cancer, however, and the 

 thus far invariable presence of Spirochceta microgyrata certainly 

 gives us no reason to change our position. In view of the small 

 number of spirochetes present, it may be pointed out as significant 

 that of the thirty-seven primary tumors with which we have dealt, 

 only two have been transplantable. 



39 (182) 



On the competency of the venous valves and the venous flow 

 in relation to changes in intra-abdominal pressure. 



By RUSSELL BURTON-OPITZ. 



[From the Physiological Laboratory of Columbia University, at the 

 College of Physicians and Surgeons.'] 



In the present series of experiments performed upon dogs, the 

 blood flow in the femoral vein was measured by means of the 

 recording stromuhr, described by the author. 1 



During the experiment the intra-abdominal pressure was sud- 

 denly raised either by pressure with the hands upon the external 

 surface of the abdomen, or by inflation of the cavity with air. 



In both cases a retardation of the venous inflow was noticed, 

 the degree of the slowing of the blood stream being in accordance 

 with the increase in the intra-abdominal pressure. Thus, in one 

 specific instance the intra-abdominal pressure was raised to 70 mm. 

 Hg. The venous pressure increased accordingly from 4.5 mm. 

 to 64.0 mm. Hg, while the blood flow decreased from 1.02 c.c. to 

 0.08 c.c. per second. 



A similar retardation occurred also with the chest widely 

 opened. Raising the intra-abdominal pressure produced no 

 marked influence upon the flow in the external jugular vein. 



A more abrupt and decisive slowing of the blood stream oc- 

 curred, when pressure was exerted with the hands. It then 

 became possible at times to produce not only a stoppage of the 



1 This volume, p. 24. 



