Proceedings of the Royal Society of London/Volume 2/Experiments to ascertain the Influence of the Spinal Marrow on the Action of the Heart in Fishes
These experiments were undertaken by the author, in order to ascertain the truth or fallacy of M. Le Gallois' conclusion respecting the action of the heart being dependent on the spinal marrow. For since the death of quadrupeds (on which M. Le Gallois operated) is so readily produced by injury to the vital organs, it appeared to Mr. Clift that fishes would be far preferable, from their being more tenacious of life.
After two or three preliminary experiments on the duration of the heart's action in carp, after being fully exposed by opening into the pericardium without any injury being done to the brain or spinal marrow, Mr. Clift next passed a hot wire from the tail to the occiput of a carp of the same size, so as to destroy its spinal marrow; and he found that the action of the heart was quickened for two or three beats, but then resumed the same rate of pulsation as before, although the voluntary muscles had lost their power and did not contract when a stimulus was applied to them.
After several repetitions of this experiment, with various modifications in the mode of conducting it, the author arrives at the following results:—
1st. That the muscles of the body of a carp can be thrown into powerful action four hours after the brain and heart are removed.
2dly. That those muscles lose all power as soon as the spinal marrow is destroyed.
3rdly. That by exposure of the heart to water in which the fish is allowed to swim, the action of the heart ceases sooner than in air.
4thly. That whether the heart is exposed or not, its action continues long after the brain and spinal marrow are destroyed; and still longer when the brain is removed without previous injury to its substance.
5thly. That the action of the heart is in general accelerated for a few beats by injuries to the brain or spinal marrow; but that destroying the spinal marrow after the brain has been separated renders the action of the heart slower for a few beats.