226 
DR. A. D. WALLER AND MR. E. W. REID ON THE 
§ V. The Wave of Contraction. 
It is not known whether or no there is any wave of contraction in the normal systole 
of the Mammalian heart, nor has it hitherto been sought for in the excised organ. 
There are no data to show whether, in the spontaneous or excited beat of the heart, 
its individual elements contract simultaneously or successively. 
Our knowledge of the wave of contraction in the heart rests entirely upon observa¬ 
tions made upon the excised organ of cold-blooded animals (Frog, Tortoise); the 
method employed has been to follow by rheotome and galvanometer the electromotive 
signs of an excitatory state at points more or less distant from a point of excitation. 
By this method, as applied by Engelmann, Marchand, and Burdon Sanderson, the 
diphasic variation indicative of the passage of a wave of negativity has been plotted 
out, and its time-relations determined ; the results thus obtained have been by 
Burdon Sanderson controlled and confirmed by photo-electrometric records. The 
velocity of the wave thus determined has been given at 20 to 40 mm. per sec. (Engel¬ 
mann), 100 mm. per sec. (Marchand), 125 mm. per sec. (B. Sanderson and Page).* 
These results apply to the excited beat of the “stanniused ” Frog’s heart. With regard 
to the spontaneous beat of the Frog’s heart, a double variation indicative of negativity, 
first at base, then at apex, has been seen, and is properly received as evidence of the 
passage of a wave from base to apex in the spontaneous systole of the excis/d heart. 
No attempt has been published, as far as we know, to determine a w T ave of contraction 
in the beat of the Mammalian heart, whether spontaneous or excited, nor has the 
wave of contraction been recognised on the heart of any animal by a mechanical 
method analogous to that which Aeby t first applied to skeletal muscle. 
We have examined the Mammalian heart for the phenomenon in question both by 
electrical and by mechanical methods. Deferring consideration of our results by the 
galvanometer and electrometer, we here briefly give the results of our application of 
a mechanical method, viz., application to the heart of a double myograph so as simul¬ 
taneously to record the movements of its different parts. With regard to the 
instrument, we need only say that it consisted of two levers, 1 to 8 cm. apart, which 
were applied to the excised heart just as in Aeby’s experiment they are applied to 
voluntary muscle. It will be well to give separately (a) the results we obtained upon 
the quiescent heart by excitation nearer to one or other of our levers; ( h ) the results 
we obtained on spontaneously beating hearts. 
(cl) Excitation of a quiescent heart, upon which rested the tw r o levers of our double 
cardiograph, at once revealed the fact that the total coordinated contraction of the 
because we used mechanical stimuli. This was necessary, but did not give us the opportunity of taking 
fine measurements of time, which indeed we did not require. 
* Engelmann; Pfluger’s ‘Archiv f. Physiol.,’ vol 17; Marchand, ibid., vol. 15 and 17; Burdon 
Sanderson and Page, ‘ Journal of Physiology,’ vol. 2, p. 384. 
j Aeby, ‘ Archiv Anat. Physiol.,’ 1860, p. 253. 
