222 
DR, A. D. WALLER AND MR. E. W. REID ON THE 
they occur, 1 st, lengthening' of the spontaneous contractions ; 2nd, abolition of the 
spontaneous contractions ; 3rd, diminished excitability to mechanical* stimuli, with 
lengthening in the period of latent stimulation ; 4th, abolition of excitability to all 
stimuli. The full effect of cold having been produced, viz., total abolition of contrac¬ 
tility, spontaneous and provoked, the application of warmth (by surrounding the 
vessel containing the heart with water at 40° C.) can restore contractility, 
spontaneous as well as provoked, the latter reappearing before the former. This 
abolition of contractility by cold, and its restoration by warmth, may be repeated 
more than once; we have repeated it as many as three tiroes. The following 
experiments illustrate these statements :— 
Experiment I.— Kitten's heart. December 5th, 1885. Record began If minute after decapitation. 
Heart in small crucible surrounded by ice. The heart at first gave 11 beats during the first 7 seconds; 
it subsequently gave strong contractions at very long intervals (about 20 seconds) for a period of 
4-| minutes. 
It continued excitable for 6 minutes longer. During the last minute of this period the prolongation 
of the latent period and of the contraction were excessive, greater than any we had hitherto observed; 
the latent period was about 2 seconds, and the length of contraction was so great and its fall so gradual 
that it could not be exactly measured; it is reproduced in Tracing 8. Its rise to a maximum occupies 
nearly 4 seconds. At end of 12 minutes post mortem, it was no longer excitable. 
The ice was removed and replaced by warm water at 40° C. The heart became excitable, but 
spontaneous beats did not return. 
The latent period was so short that we did not measure it. 
The duration of contraction was shortened, and it was noteworthy that the ascent of the curve was rapid 
while its descent was still gradual. 
Experiment II.— Babbit’s heart. December 5th. The record began 1 minute after decapitation, the 
heart being in a cup surrounded by ice. 
It only beat for If minute, giving altogether 13 spontaneous beats. 
It continued excitable to direct stimulation for about 3 minutes longer. 
After the heai’t had ceased to be excitable it was removed from the influence of the ice, and was 
subjected to that of warm water at 40° C. 
Within 1 minute of application of warmth the heart recommenced to beat spontaneously —at first 
slowly, afterwards more rapidly. 
Excited contractions followed so rapidly upon mechanical excitation that we could not measure the 
latent period with the rate of revolution employed. 
Minutes after application of warmth. Frequency of beat. 
8 beats per 15 seconds. 
b JJ >1 !! >) 
O 
& 11 11 11 11 
o 
^ ii n ii n 
9 
*“ ii ii ii ii 
Observation stops 30 minutes post mortem, the heart still beating feebly. 
It is noteworthy that after the application of cold during 10 minutes, by which spontaneous contrac- 
3 min. 
5 „ 
8 „ 
H „ 
14 „ 
* We found mechanical stimulation more effectual as well as more convenient than stimuli from the 
induction coil. 
