192 



Transactions of the Canadian Institute. 



[Vol. VII. 



is seen gradually to right itself. At 

 3, on the animal being placed hori- 

 zontal, the pressure went for a 

 moment above the normal line, the 

 compensation still continuing. 



But if the vertical posture be 

 maintained for a long time this 

 compensation will fail, as shown by 

 Mr. Hill on certain animals\ and as 

 often shown clinically when people 

 faint from long standing. The 

 swelling of horses' legs from long 

 standing is another familiar illustra- 

 tion of the same thing. 



Tracing 6 shows compensation 

 for the feet-up posture. At 3 the 

 feet were raised and the pressure in 

 the carotid temporarily rose, but 

 although the animal was kept in this 

 position it soon fell to the normal 

 line, and when the animal was placed 

 horizontal at 4, the compensation 

 continuing for a while, the pressure 

 actually went below the normal. 



When the canula is placed in 

 the proximal end of another artery, 

 e.g., the femoral, as in Tracing 7, 

 the same phenomena are observed. 

 Then, of course, the vertical feet-up 

 posture causes a fall in pressure, and 

 the vertical feet-down a rise. This 

 tracing illustrates well again the rule 

 that the rise produced in the pres- 

 sure in the vessels of a pole of the 

 body by lowering that pole is not 

 so great as the fall produced by 

 raising it. 



Ibid. 



