216 
DR, A. D. WALLER AND MR. E. W. REID ON THE 
PAGE 
5. Dui’ation of systole. 220 
6. Decline in warm chamber . 221 
7. Effect of cold on duration of systole. 221 
8. ,, „ latency. 225 
9. Wave of contraction in ventricle (excited beat). 227 
10. „ „ strip of ventricle. 227 
11. „ „ right auricle.... 227 
12. Wave (?) of contraction in spontaneously beating ventricle. 231 
13. Wave of contraction in spontaneously beating ventricle. 231 
14. ,, ,, Frog’s ventricle (excited beat). 228 
15. „ ,, „ ,, (spontaneous beat). 228 
Photographs. 
1. Electrical variations of Frog’s auricle and ventricle 
2. ,, ,, „ ventricle . 
3. ,, ,, Rabbit’s ventricle.... .. 
4. ,, ,, Cat’s ventricle. 
5. Ventricle of Dog'. ... ... 
6 . „ „ ' ... 
7. I. i) . . 
237 
237 
238 
238 
239 
240 
242 
§ I. Introduction. 
Our attention was directed to the action of the excised Mammalian heart in the 
course of experiments relating to the electromotive action of various tissues, by our 
observation of the fact that the electromotive variations indicative of action outlast 
visible contractions ; secondly, that the contractions of the excised organ are of an 
extraordinarily prolonged character. 
We consequently pursued our observations (1) by the galvanometer, (2) by the aid 
of the graphic method, (3) by the capillary electrometer (Lippmann). By the 
galvanometer and by the electrometer we observed the electrical changes consequent 
upon spontaneous or provoked contraction, and in the absence of visible contraction. 
By the graphic method we determined the duration of spontaneous and of excited 
beats, and, with regard to the latter, the length of the latent period at various times 
after excision. Incidentally we also observed the time during which the rhythmic 
beat persisted after excision and the character of that beat under varying conditions 
of temperature. By both methods we were able in favourable cases to follow the 
progress of the wave of contraction, both spontaneous and excited. Our observations 
were made on the hearts of Cats, Dogs, Rabbits, Guinea-pigs, Rats, and Sheep. 
§ II. Tie during which spontaneous contractions continue after excision of the 
heart.—Mode of decline. 
The statements as regards this point which are most generally quoted are based upon 
the observations of Czeiimak and Piothowsky, who found for the heart’s beat of 
