Medical Apparatuses 423 



which the compression supports in their action. Through the effect 

 of this contraction, the first half of the expiration is made quickly 

 and energetically; but the second half is made so slowly and so im- 

 perceptibly that there is a sort of pause between the inspiration and 

 the expiration. This pause which should in any case be added to the 

 expiration and the length of which has been, according to my ob- 

 servations, from two to six seconds, is increasingly longer as the in- 

 spirations are fewer. 



Vivenot has tried to express these different modifications of the 

 respiratory rhythm by the following graph (Fig. 9) , which I borrow 

 from his long work (p. 251), and in which the solid line indicates 

 the normal respirations, and the dotted line the respiration under 

 compressed air, the whole during fifty-some seconds. 



Circulation. The memoir published by Vivenot in 1865 in the 

 archives of Virchow contains detailed information about the modi- 

 fications in his pulse under the influence of compression. These 

 explanations are accompanied by numerous graphs obtained by 

 means of the sphygmograph of M. Marey; I reproduce here the 

 most characteristic: 



A rapid glance at the curves shown below reveals that under 

 the influence of compressed air they undergo considerable modifica- 

 tions in their original forms; closer attention shows that all parts of 



Fig. 9— (bis). 



the curve are so essentially changed that their analysis requires care- 

 ful dissection of separate segments of the curve. 



We see that in all the curves without exception, under the in- 

 fluence of compressed air, the height of the curve decreases. The line 

 of ascent, more or less abrupt originally, becomes more oblique; 

 the apex seems more rounded, and because of the lessening of the 

 amplitude, the line of descent, still less abrupt, finally is bent into the 

 form of a wave which is more or less convex on the right. Because 

 of the decrease in the height of the curve, the angle formed by the 

 intersection of the ascending line and the descending line of the pulsa- 

 tion inscribed and which under normal atmospheric pressure measures 

 about 45° is considerably blunted; and also, because of the more 

 oblique direction of the line of ascent, the apex of the top of the 



