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22 CARDIOGRAPH TRACINGS 
generating the retrograde current to close the valve, the change in 
direction of the curve being produced, first by the relaxation of the 
heart causing it to advance, and then by the partial collapse of the 
aorta causing it again to retire. This rise and fall is also clearly shown 
in Fig. II, f. 
It can be seen in Fig. IV that in the pulse of 90 the undulation f 
is not so long as in the quicker ones, and in the slow curves it is 
shorter still, but the want of sharpness and the blending of the neigh- 
bouring rises prevent any accuracy being attainable in the latter 
cases. 
The immediate effect of the closure of the semilunar valves, at the 
end of the fall f, is to cause a check to the descent of the lever (4), 
as the aorta is no longer emptying itself heartwards; but this is very 
soon counteracted by the consequent repletion of the coronary arte- 
ries,* which, as can be easily shown on the post-mortem heart, in- 
creases the diameter of the ventricles and makes them recede, drawing 
the apex back, further than during any other part of the revolution. 
During the rest of diastolé, other minor forces come into play which 
are not easy to trace. 
Figures VII, VIII, 1X are given to show that under different con- 
ditions the various rises and falls may be made to assume different 
degrees of importance. In Fig. VIII, where the greater part of the 
weight of the heart rests against the chest-wall, it is particularly to be 
noticed that the fall after g, before which the semilunar valves close, 
commences from the very top of the trace, showing that the main force 
by which the heart is made to recede, which from the great length of 
the down stroke must be considerable, does not commence until after 
the closure of the aortic valve, which supports the theory of the cause 
of the active ventricular diastolé noticed above. 
A superficial examination of cardiograph tracings is sufficient to 
convince the observer that when the heart beats slowly the jirst part 
of the revolution, namely, from the commencing systolé until the 
closure of the semilunar valves, bears a smaller ratio to the whole than 
in quick pulses. This led the author to make a series of measurements 
of these ratios, on the assumption that the ventricles commence to 
contract at the origin of the main rise, and that the semilunar valves 
close at the end of the fall f. 
To ensure accuracy, the trace was placed on a flat piece of wood, 
to which was attached a ledge, along which it could be made to slide. 
* That the active diastolé of the ventricles results from the congestion of the 
coronary vessels was discovered by Briicke; and I regret that my ignorance of his 
observations, published in the “Sitzungsberichte der Wiener Akad. der Wiss.,” Nov., 
1854, XIV. p. 845, prevented my referring to them, in a paper on the same subject, 
in this Journal for May, 1869. (Supra, p. 3.) 
