THE CIRCULATION OF THE BLOOD AND LYMPH 85 



but a moment at the maximum, then immediately descending 

 forms a ' peak,' and not a plateau. 



While perhaps it is hardly possible at present to decide 

 finally between the plateau and the peak, yet the bulk of the 

 evidence goes to show that the former is not, as the advocates 

 of the peak have claimed, an artificial phenomenon, but 

 does in reality correspond to that continuation of the systole 

 of the ventricle, that dogged grip, if we may so phrase it, 

 which it seems to maintain upon the blood after the greater 



FIG. 24. COMPARISON OF PRESSURE-CURVES OF LEFT AURICLE, LEFT VEN- 

 TRICLE, AND AORTA, (v. FREY.) 



Recorded by elastic manometers with air transmission. The ventricular curve shows 

 a ' peak.' 



portion of it has been expelled. This conclusion is essentially 

 in accordance with the results of Chauveau and Marey, 

 obtained long ago by means of their ' cardiac sound,' which 

 was in principle an elastic manometer, though of somewhat 

 faulty pattern (Fig. 25). 



It consisted of an ampulla of indiarubber, supported on a frame- 

 work, and communicating with a long tube, which was connected 

 with a recording tambour. The ampulla was introduced into the 

 heart through the jugular vein or carotid artery in the way already 



