ACTION OF THE EXCISED MAMMALIAN HEART. 
237 
out of our control: we can only submit to the criticism of our readers examples, the 
data of which we have obtained by its means. All these data have been furnished 
by the same capillary tube. The review of these examples shows (I) that our instru¬ 
ment was perfectly capable of giving the record of diphasic variations,'* (2) that in 
some cases only a monophasic variation is revealed. Our opinion is that Fact 1 is 
sufficient argument for accepting Fact 2 as a true indication of a single phase, and not 
regarding it as the compound indication of two phases. Our experiments showed us 
Photograph 1. 
Frog’s heart spontaneously beating, showing auricular variation, followed by ventricular. 
Note. —All photographs read from left to right. The rates of movement of the photographic plate are 
indicated on the plates themselves. Two rates were usually employed, the slower of about 1 minute 
= ’44 second, the quicker of about 1 minute = '03 second. 
Photograph 2. 
arinnniuiruinrinnrLnJuxriJlrinrinrinrmniinnnxiri nn nnnnn nnn unnnnnnnr 
Shows double variation of spontaneously-beating Frog’s ventricle. 
The electrical phases are in opposite direction at beginning and at end of beat; first phase, base negative 
to apex ; second phase, apex negative to base. 
A simultaneous record is made of the movements of a lever resting on the ventricle. (Apex to H 3 S0 4 , 
variation SN.) 
that a double variation seen by the galvanometer is also seen and recorded to be 
double by the electrometer (Photos. 1 and 2) ; they showed further, as we expected, 
that a variation seen as simple with the galvanometer could be shown to be composed 
of two phases when the electrometer was put in circuit instead of the galvanometer. 
The fact, however, for which our previous experiments had not prepared us, was that 
* We also obtained the diphasic variation of a single twitch of the Frog’s gastrocnemius excited by an 
induction shock. 
