ACTION OF THE EXCISED MAMMALIAN HEART. 
243 
much retarded transmission from part to part along nerves or with muscular conduc¬ 
tion is difficult to saj with certainty ; the entire similarity of the wave with a muscular 
wave is, however, sufficiently obvious. Finally, when transmission can no longer be 
effected, the heart responds to local excitation by a monophasic variation which may 
be temporary—indicative of local discharge of action,—or permanent—indicative of 
injury of tissue. 
No portion of our inquiry gave us more trouble and doubt than the results of the 
mechanical exploration at base and apex of the spontaneously beating heart. Almost 
without exception we obtained apparently movement at apex antecedent to movement 
at base. All possible care was exercised, and we have given our results. We have 
been careful to say no more than that “ the movement of the lever resting near the 
apex precedes that of the lever resting near the base.” 
Sometimes the contraction of the apex was visibly antecedent to contraction at the 
base—exceptionally, the precedence was with the base. In the case of the Frog’s 
heart this was always the case. 
A desire to obtain the variation of the absolutely normal and unexposed heart led 
us to the exploration of the human subject with the following result, viz., auricular 
followed by ventricular negativity anteceding respectively the auricular and ventri¬ 
cular events. We could obtain no evidence of a diphasic ventricular variation, and 
we have yet to exclude the possibility of the observed variation being caused by 
alteration of contact by the heart’s impulse.'"' 
* I have since ascertained that the variation on Man is in reality due to an action current, and not to 
alteration of contact. The variation precedes the cardiac impulse; it may also be observed when the 
hand and foot are dipped into two vessels of salt solution connected with the electrometer. Under these 
circumstances the variation is still observed preceding the cardiac impulse.-—A. W., July 5, 1887. 
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