52 ox DIGITALIS, WITH SOME OBSErtVATIOXS ON THE URINE. 



it caused only by a difference in the rapidity with which the 

 blood is impelled into the arteries, and the fact that we notice, 

 that while the average oscillation at the cardiac beats in one 

 case is -f^ths of an inch, that at inspiration is 1 inch. Though 

 my own observations are as yet too incomplete to enable me 

 to eliminate the disturbing effect of respiration, and the obser- 

 vations of Winogradoff,* in the short abstract that I have seen 

 of them, are liable to the same fallacy, they yet seem to render 

 the increase of force somewhat probable. It is obvious, how- 

 ever, that by examining a tracing by an instrument such as 

 the registering hremadynometer of Setschenow, which was em- 

 ployed by Winogradoff, and which registers at once both the 

 cardiac pulsations and the respirations, and comparing its 

 indications with those which we have seen would occur from 

 increase or diminution of the heart's force, the problem might 

 be solved with mathematical accuracy, not only for digitalis 

 but for any other poison. 



Though unable at present thus to afford complete proof of 

 the increase of force, there is another line of argument open, 

 viz., the effect of increase or diminution of the contractile 

 power of the heart upon its impulse. If the contractile 

 power be increased relatively to the resistance to be overcome, 

 or arterial tension, the contraction will be rapid, and the 

 heart's impulse abrupt and strong. If the power be lessened, 

 the contraction will be slow, and the impulse consequently weak. 



Though this necessarily follows from physical laws, some 

 might yet be inclined to urge as an objection — " But you find 

 this strong and abrupt impulse in nervous palpitations and 

 weakly persons, and is it to be supposed that the power of the 

 heart is increased in these ? " But in these cases, though the 

 power of the heart be not absolutely increased, it is relatively 

 to the resistance, for the arterial tension in these cases is low. 

 After the administration of digitalis, we find not only that the 

 impulse is abrupt and strong, showing increased power relative 

 to the tension, but that the tension itself is increased (Exp. V, 

 3, 25' 50''), and the absolute increase of contractile power is 

 completely proved. 



* Tear Book SydenJiam Society, 1862, p. 452. 



