But another specially interesting fact with regard to epilepsy is this, that, a few days after the operation, whether made on the spinal cord or the sciatic nerve, it is found that an area of skin on the same side with the nerve destroyed or the spinal cord injured, which is limited by the line extending from the anterior extremity of the eye to the end of the nose, thence, comprising the upper lip, running along the neck to the shoulder, and then in a straight line to the posterior extremity of the ear, and, lastly, to the posterior angle of the eye, by degrees loses certain faculties and acquires new ones. The sensation of pressure, of squeezing, of heat, cold, or electricity, of pain in a word, all disappear; only the faculty of feeling tickling persists, and that appears exaggerated. In an experiment which I made some years ago, this effect followed within two hours of the operation on the upper spinal cord.
It is seen at the same time that tickling this zone gives rise at first to involuntary twitchings in the muscles of the jaw, of the eyes, and of the nose, on the same side; by degrees those twitchings become more strong and more general, then they manifest themselves on the other side also, and after a few weeks the animal has regular convulsions after each tickling of the zone, which lastly culminate in a regular attack of epilepsy, of which the features are the following: When the attack begins, the head is drawn first, and with great violence, at times toward one shoulder, at times toward the other. This has been explained by the contraction of the muscles of the neck. The mouth is drawn open by the same cause, and the muscles of the face and of the eyes, which had twitchings, now contract violently also. At this period it would appear that the muscles of the larynx are contracted to some extent. At all events, it appears that the vocal cords are contracted, for not unfrequently the animal utters an inarticulated, unnatural, sharp cry, which may be taken for the passage of air through the obstructed larynx. It then falls. The muscles of the legs are contracted stiff, those of the chest are thoroughly so; very soon all the muscles are the seat of convulsions. Respiration, which was in no little degree impeded during the time that the muscles of the chest were rigid, now becomes more frequent but very irregular. After a while the animal recovers, and remains in a state of stupidity for some time. It is not unfrequent to observe in these epileptic seizures fits of insanity—if I may use such a term when speaking of Guinea-pigs, but that word only will make my meaning understood. When these animals have been suffering for some months, it is seen that they have fits without apparent provocation; that is to say, spontaneously.
When they recover from the epileptic taint, all the phenomena observed about the zone of skin in the neck and face recur in the reverse order; that is to say, all the different sensations return by degrees, at the same time that the hair of that region falls, and new