238 
DR. A. D. WALLER AND MR. E. W. REID ON THE 
the electromotive change accompanying the beat of the ventricle is not alwavs 
composed of two phases, it is sometimes expressed in its photograph as a single 
variation (Photos. 3 and 4). This then is the fact ; our opinion concerning it is that, 
having regard to the rapidity with which the instrument may be shown to act to verv 
brief changes in very rapid succession, the single variation observed under these 
circumstances is proof of a practically single and simultaneous change taking place 
Photograph 3. 
Spontaneous variations of Rabbit’s ventricle immediately after excision. These are in this case 
monophasic, and such as to indicate that the apex became negative to the base at each beat. (Apex 
to Hg. Variation N.) 
Photograph 4. 
Spontaneous variations of Cat’s ventricle. These are monophasic, and indicate that the base becomes 
negative to the apex. The electromotive variations show dicrotism which corresponded with the 
dicrotism of visible beats. Time post mortem 5 minutes. (Apex to H 3 S0 4 . Variation S.) 
throughout the ventricle, and disproof, or at least failure of proof, of the passage of 
a wave of excitation in the contractile substance. Our previous experiments by 
mechanical and by galvanometric methods had furnished the demonstration under 
certain conditions of the passage of a wave of excitation and of contraction at rates 
slow enough to be measurable, and the demonstration is confirmed by the electro¬ 
meter (diphasic variation, Photo. 5). But our previous experiments by mechanical 
