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THE POPULAR SCIENCE MONTHLY. 



At this moment I took two or three inhalations of oxygen, and at 

 once the pulse fell to 71. Then I omitted the oxygen, and moved a 

 little, when the pulse rose to 100, falling again to VO when I returned 

 to the oxygen. Ten times during an interval of one hour and twenty 

 minutes, and with the pressure ranging between 40 and 50 centimetres, 

 I at will produced these sudden oscillations, causing my pulse instant- 



ly to rise or fall 20 beats. I may add that this is an experiment which 

 I do not mean to repeat, having suffered during that evening slight 

 congestive symptoms, which I attributed to these sudden changes of 

 cerebral circulation. 



On the other hand, those experiments in which oxygen is respired 

 continuously are not followed by any injurious effects. Fig. 4 states 



