ACTION OF THE EXCISED MAMMALIAN HEART. 
223 
tlons and excitability were entirely abolished, the heart, under influence of moderate warmth, recovered 
so as to beat for 20 minutes, giving during that period more than 150 beats. 
Experiment III .—Small Rabbit. December 18th, 1885. Decapitated at 12. Heart excised and placed 
in porcelain crucible surrounded by ice. 
Time. 
12 . 2 . 
12,7. 
12.9. 
12.13. 
12.14. 
12 . 20 . 
12.24. 
12.26. 
12.28. 
12.28-30. 
12.40. 
12.44. 
12.48. 
12.50. 
12.55. 
1 
1 . 10 . 
1 . 20 . 
Record begins. 
Spontaneous beats have ceased. 
Excitability has ceased. 
Warmth applied (water at 40°). 
Spontaneous beats renewed. 
Cold applied (melting ice). 
Spontaneous beats ceased. 
Excitability ceased. 
Warmth applied (40°). 
Spontaneous beats. 
Cold applied (0°). 
Excitability ceased. 
Warmth (40°). 
Spontaneous beats. 
Excitation, followed by “delirium.” 
Cold apjjlied for 10 minutes ; quite inexcitable. 
Warmth applied; a single spontaneous beat. 
Heart quiescent and inexcitable. 
Remark .—The excitability of the heart was three times in succession abolished by cold and restored by 
warmth. 
We have gone further than this : we have frozen the heart until it was quite hard 
by placing it in a capsule surrounded by ice and salt, and have observed its spon¬ 
taneous contractions when it has been thawed. 
Experiment IV.—December 19th, 1885. A Cat was decapitated at 11.59, the heart quickly excised, 
and placed in a porcelain capsule surrounded by ice and salt; by 12.14 it was frozen hard; it was 
removed from the freezing mixture and placed in another capsule surrounded by water at 42° C. It 
commenced to beat spontaneously at 12.24J, and a lever was at once placed upon it, and a record taken 
on the smoked cylinder. 20 spontaneous beats were recorded, and the heart remained excitable to the 
prick of a needle till 12.33. 
We have gone further still: we have left the freshly excised heart in a freezing 
mixture for 3 hours. Its contractility did not, however, return. The heart’s beat 
was recorded on the smoked cylinder in all the above experiments. 
Warmth, notwithstanding its restorative effect upon a cooled heart, is not favourable 
to the long persistence of its rhythmic contraction after excision, nor even if it be left 
in the body of the recently killed animal. We have noticed at the outset that the 
excised and cooling heart usually beats for a longer period than a heart left in the 
body ; we observed later that an excised heart beats for only a very short period in the 
warm chamber at 38° C., and we may add that a small, and therefore rapidly cooled, 
heart (Rabbit) outlasts a large and slowly cooling heart (Sheep). As of other tissues, 
