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 70 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 instantly
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