1st Experiment. A large incision was made immediately below the occiput. The posterior half of the first vertebra was then removed and the spinal marrow laid bare, at the same time a considerable incision was made in the great glutæus muscle, in order to expose the sciatic nerve. A slight incision was made in the heel; no blood escaped from any part. A wire which communicated with one extremity of the battery was put in contact with the spinal marrow, whilst the other was applied to the sciatic nerve. All the muscles of the body were in an instant agitated with convulsive motions which resembled a violent shuddering. The strongest convulsions were on the left side; at each time of renewing the electric contact by moving the second wire from the haunch to the heel the knee being previously bent, the leg was thrown out with so much force, that it threw down one of the assistants who in vain endeavoured to prevent the extension.
2d Experiment. The left phrenic nerve was laid bare towards the external edge of the sterno-thyroideus muscle, three or four inches above the clavicle; as this nerve goes to the diaphragm, and as it communicates with the heart by the eighth pair, it was expected, that by throwing the galvanic fluid through it, the action of respiration would be renewed. In consequence a small incision having been made under the cartilage of the seventh rib, the point of an insulated wire was placed in contact with the diaphragm, whilst the other was applied to the phrenic nerve of the neck. This muscle, the principal agent of respiration, contracted immediately, but with less force than was expected. As I knew by numerous experiments that we could produce the most powerful effects from the galvanic fluid, by leaving the extreme communicating wires perfectly in contact with the parts on which we wished to operate, whilst, in order to complete the electric chain, we carried the end of the wires the length of the plates, into the last trough of one of the poles and immediately plunged the other wire into the last cell of the opposite side, I had recourse to this measure without loss of time. The success was truly astonishing; instantly commenced a strong and laborious respiration. The chest rose and fell; the abdomen was pushed forward and then flattened, and the diaphragm contracted and relaxed. All these motions appeared without interruption as long as I continued the electric excitement.
In the opinion of many scientific persons who were witnesses of this scene, this experiment was perhaps the most striking that had ever been made with an electrical apparatus. It should be recollected that during half an hour at least, before this, the body had been nearly exhausted of blood and the spinal marrow had been much lacerated.
No pulsation could be perceived either in the heart or at the wrist.
3d Experiment. The suborbitar nerve was laid bare at its exit from the suborbitar foramen. One of the conducting wires was applied to the nerve and the other to the heel; the most extraordinary grimaces were produced. All the muscles were put simultaneously in action in a frightful manner; rage, horrour, despair, anguish and frightful smiles united their hideous expression in the face of the assassin. At the sight of this, many of the spectators were obliged to leave the room and one of them fainted.
4th Experiment. The last galvanic experiment was made by transmitting the electric fluid from the spinal marrow to the cubital nerve near the elbow; the fingers moved quickly like those of a performer on a violin; one of the assistants who endeavoured to keep the hand shut, found that it opened in spite of his efforts. A wire was applied to a slight incision made at the end of the first finger; the hand had been previously shut; the finger was instantly extended, and, after a convulsive agitation of the arm, the dead man seemed to point his finger at the spectators, some of whom thought that he had come to life.
An hour was consumed in these experiments.
[116] It is shewn by the beautiful experiments of M. Legallois, that the heart derives the principle of its forces from the spinal marrow, and from the whole spinal marrow, since the destruction of one of its three portions can arrest completely the circulation. The destruction of the spinal marrow does not entirely annihilate the motions of the heart; but it weakens them sufficiently to prevent the circulation, and this weakening is so much the greater, as the portion of spinal marrow destroyed is larger. It may be presumed from this, that notwithstanding the weakening which follows the removal of a part of this marrow, the circulation may still continue if we lessen the sum of the forces which the heart must expend to maintain it. For this it is only necessary to diminish by ligatures on the arteries, the extent of the circle to which the heart distributes the blood. This conjecture is confirmed by experiment. It has been seen, for example, that the destruction of the marrow which is very suddenly fatal in full grown rabbits, ceases to be so, if before doing it the abdominal aorta is tied between the coeliac and the superior mesentric arteries. The application of the same principle to other parts of the body leads to a still more surprising result, it is this, that in order to support life in rabbits of a certain age, after having destroyed the cervical marrow, it is necessary first to cut off the head. They will be completely dead if the marrow be destroyed before they are decapitated; this arises from the fact, that by cutting off the head all this part is taken out of the domain of the circulation, and that by it the heart having need of less force to continue its function, we can weaken it by the destruction of the cervical marrow without its ceasing to perform it.
[117] When an animal is thus struck, it is not certain that the concussion has not extended its effects upon a greater or less part of the spinal marrow; and it is not known consequently if the motions of the heart would not cease, even when asphyxia might be prevented by means of artificial respiration.