1894.] the Force of Gravity on the Circulation. 195 



tambour or piston recorder. The cerebral venous pressure was taken 

 in the torcula Herophili by the method described by me in the 

 before-quoted paper. 



The respiratory tracings were taken by means of a broad band of 

 strapping passed round the thorax and connected to either side of a 

 Paul Bert tambour. The changes of position prevented the use of 

 any more accurate method for recording the respiration. 



The results of the research are shown in a series of tracings, from 

 which the following conclusions are drawn : 



1. That the force of gravity must be regarded as a cardinal factor 



in dealing with the circulation of the blood. 



2. That the important duty of compensating for the simple hydro- 



static effects of gravity in changes of position must be ascribed 

 to the splanchnic vaso-motor mechanism. 



3. That the effects of changing the position afford a most delicate 



test of the condition of the vaso-motor mechanism. 



4. That the amount of compensation depends largely on individual 



differences. 



5. That the compensation is far more complete in upright animals 



such as the monkey, than in rabbits, cats, or dogs, and, there- 

 fore, is probably far more complete in man. 



6. That in some normal monkeys over-compensation for the hydro- 



static effect occurs. 



7. That in the normal monkey and man gravity exerts but little 



disturbing influence, owing to the perfection of the compen- 

 satory mechanism. 



8. That when the power of compensation is damaged by paralysis 



of the splanchnic vaso-constrictors, induced by severe operative 

 procedures or by injuries to the spinal cord, by asphyxia, or 

 by some poison such as chloroform or curare, then the influence 

 of gravity becomes of vital importance. 



9. That the feet-down position is of far greater moment than the 



feet-up position, because when the power of compensation is 

 destroyed the blood drains into the abdominal veins, the heart 

 empties, and the cerebral circulation ceases. 



10. That, generally speaking, the feet-up position occasions no ill 



consequence. 



11. That the horizontal and feet-up positions at once abolish the 



syncope induced by the feet-down position by causing the 

 force of gravity to act in the same sense as the heart, and 

 thus the cerebral circulation is renewed. 



12. That firmly bandaging the abdomen has the same effect. 



While the heart remains normal, and so long as the mechan- 

 ical pressure is applied to the abdominal veins, the blood 

 pressure cannot possibly fall. 



