194 Prof. L. Hill. The Influence of [Dec. 13, 



bubble index in the apparatus exhibited large cardiac and respiratory 

 undulations. 



Experimenting on dogs, I found that exactly the same thing 

 occurred. The normal cerebral pressure became markedly negative 

 in the feet-down posture, and positive in the feet-up posture. 



For the further investigation of the subject, I constructed an 

 animal holder which could be swung round a horizontal axis. In 

 this axis the cannula connected with the vessel under observation was 

 always placed, and the cannula itself was connected with a fixed 

 hydrostatic manometer. 



The " hydrostatic and dynamic moments," to use Hermann's ex- 

 pression, were investigated and separated, not by attempting to find 

 the indifferent point, but by carefully observing the effects of dividing 

 and stimulating the vagus and splanchnic nerves and spinal cord, and 

 by watching the influence of anaesthetics, curare, and asphyxia. 



The research has been carried out upon rabbits, cats, dogs, and 

 monkeys, and the same general results have been obtained from all. 

 The animals were anaesthetised in all the experiments, and were placed 

 upon a board with the limbs fully extended in the same direction as 

 the longitudinal axis of the body. 



The experiments group themselves under the following headings : 



A. Effects on the Circulation. 



i. Normal effect on arterial pressure. 



(a) With carotid artery in axis. 

 (6) "With femoral artery in axis, 

 (c) With splenic artery in axis, 

 ii. Normal effect on venous pressure. 



(a) With splenic vein in axis. 

 (6) With femoral vein in axis, 

 (c) With torcula Herophili in axis, 

 iii. Influence of anesthetics. 

 iv. Effect of dividing the vagi. 

 v. Effect of dividing the spinal cord. 



(a) Influence on heart. 

 vi. Effect of dividing the splanchnics. 

 vii. Influence of respiration and asphyxia, 

 viii. Influence of curare. 



B. Effects on Respiration. 

 i. Normal effects. 

 ii. Effect of dividing the vagi. 



The venous pressures were recorded by means of a manometer 

 filled with sat. MgSOi sol. and placed in connection with a delicate 



