386 Dr. S. W. Patterson. The Antagonistic 



I. II. IV. 



Fig. 6. — Ventricular Volume Curves. Eead from left to right. Systole downwards. 

 Time 1/5 second. (I) Medium venous inflow, normal, C0 2 , adrenalin ; (II) small 

 venous inflow, adrenalin ; (III) full venous inflow, adrenalin, adrenalin with C0 2 . 



be more convex to the abscissa, as the blood is driven out more slowly 

 towards the end of systole. Diastole sets in rapidly and continues till, after 

 about two-thirds of its course, it becomes less rapid, and then rises again 

 parallel to its original curve to the maximum diastolic position, when the 

 curve turns sharply into the downstroke of ventricular systole. With 

 greater or smaller filling, the shape of the curve is steeper or more 

 gradual ; but only with hearts abnormally slowed by vagus stimulation is 

 there a diastolic portion running nearly parallel with the abscissa ; the 

 part appearing to run parallel with the abscissa for an instant and inter- 

 rupting the usual diastolic curve being probably due to the ventricles being 

 drawn up slightly through the movable elastic diaphragm of the cardiometer 

 by the contracting auricles. 



When C0 2 is administered, the systolic downstroke is less steep, while 

 the diastole is lengthened so that the next auricular systole occurs at the 

 ?time that the heart volume has reached the maximum diastolic position. 



With adrenalin the systolic downstroke is steeper than normal, and then 

 reaches the minimum gradually, while the diastolic expansion is interrupted 

 .by the next auricular systole before the maximum dilatation is reached. In 

 anany cases, with small venous inflow, the heart volume curve presents a flat 

 top, the systole continuing after the ventricle has expelled the blood in it. 

 This is especially marked in curves obtained with small venous inflow after 

 injection of adrenalin, when the. major part of the output per beat is ejected 

 in the first part of systole. 



With full venous supply after adrenalin the systolic and diastolic parts of 



the curve are smooth and rapid ;* but when CO2 is administered at the same 



* The smoothness of the curve with adrenalin, however, is probably due to the period 

 of the recorder being too slow ; for using the recorder designed by Piper (14), in Berlin, 

 which turns the volume changes into pressure changes and records these by a beam of 



