Medical Apparatuses 



425 



In no case did I find this change in the curve lasting, but this 

 effect, agreeing with. the results which we obtained for the pulse rate, 

 in favorable cases is prolonged for a few hours. Curve d, in Figure 

 12, furnishes an example of a curve rising and regaining its original 

 form, not immediately, but twenty minutes after the return to nor- 

 mal pressure. 



Fig. 12 



To establish the truth of the assertion which we have already 

 accepted, that the vestige, remaining after the treatment, of an 

 effect upon the tracing has already disappeared after several hours, 

 one may use curves obtained upon myself May 26, a day on which I 

 had had two experimental treatments in compressed air. If we com- 

 pare the curve obtained on that day before the first treatment, at 

 eight o'clock in the morning (Fig. 12, a) with the corresponding 



Fig. 13 



curve of the second treatment, that is, taken at half-past two in the 

 afternoon (Fig. 13, a), one can note no essential difference between 

 these two pulse tracings. After this period of four hours and a half 

 there is no perceptible sign of the effect still noticeable at ten o'clock 

 on curve b of Figure 13; still less should we expect to find the persist- 

 ence of this effect from one day to another. 



Now, to grasp the value of the differences so far found, we should 

 picture the different elements of the curves as the expression of these 

 changes. 



The irregularity in the ascending line which coincides witn the 

 systole of the heart is produced by the blood wave expelled by the 

 contraction of the heart, and this wave, tending to spread in all direc- 

 tions, partly urges on the blood current and partly exerts an excentric 

 pressure upon the walls of the vessels which it stretches. The ascend- 

 ing part of the curve (line of ascent) therefore corresponds to the 

 arterial diastole. The more easily the blood flows in the capillaries, 



