ACTION OF THE EXCISED MAMMALIAN HEART. 
229 
organ occurred as a wave starting from the point of excitation. The lever nearest to 
the excited point commenced to rise sooner than the more remote one, the difference 
being sometimes so considerable as to be plainly visible without record. 
This, which is the fundamental fact, was clear and unmistakable in ventricle and in 
auricle, and we may anticipate upon a future section of our paper by adding that the 
galvanometric indication of the passage of a wave of negativity was equally clear and 
unmistakable in the form of a diphasic variation. 
We thus learned that the wave known to occur in the excited beat of the “ stanniused ” 
Frog’s heart occurs under similar conditions in the Mammalian heart, i.e., in the excised 
quiescent organ. As may, however, be expected, the experimental shortcomings of the 
Mammalian heart are more frequent than in the case of the cold-blooded organ ; 
complete and typically illustrative results are not obtained without fail, and variations 
are so great that a normal time-value of the wave cannot well be given. 
Biit we have obtained records conclusively showing the existence of the wave in 
the ventricle and in the auricle, both in the entire organ and in strips of muscle cut 
therefrom. The experiments we have made in relation to this point are given in the 
accompanying resume (Table F). Tracing 9 is an example of the wave of contraction 
in the left ventricle. Tracing 10 is an example of the wave of contraction in a strip 
of the right ventricle. Tracing ] 1 is an example of the wave in the right auricle of 
the Dog’s heart. Table G contains the results of the few measurements we have 
made of this wave. 
The results thus obtained on the Mammalian heart led us to apply the same 
method to the heart of the Frog; for this purpose we employed levers 5 mm. apart. 
As far as we knew, this had not yet been done : Marchand had attempted to obtain 
evidence concerning the rate of the contraction wave by alternately exciting the 
ventricle, near and far, from a part upon which a single lever had been adjusted; his 
attempt failed, as was to be expected, from the variability of the latent period. The 
double lever, by means of which the contractions of two parts near and far from a 
point of excitation are simultaneously recorded, avoided this source of error, and by 
it observations may be multiplied. Our measurements thus made give for the 
rapidity of the contraction wave in the Frog’s ventricle, at between 8° and 12° C., a 
rapidity of between 30 mm. and 90 mm. per sec. These measurements are given at 
the end of Table F, and are illustrated by Tracing 14. 
( b .) The Spontaneous Beat .—-The evidence which we had obtained of the occurrence 
of contraction consequent upon excitation of the quiescent organ in the form of a 
wave starting from the excited point naturally led us to inquire whether or no a 
similar wave of contraction takes place in the normal spontaneous contraction. The 
testimony of the galvanometer is to the effect that such a wave does occur in the 
spontaneous beat of the excised Frog’s heart; the rheotome is here inapplicable, but 
the double variation observed from the beating heart, when led off at base and apex, 
is such as to indicate the two phases : (1) negativity of base, (2) negativity of apex, 
