The morbid change in the nerve-centre is probably, in the vast majority of cases, an interstitial atrophy, tending either to recovery, or to the gradual establishment of gray degeneration, or yellow atrophy, of considerable portions of the whole of the posterior root, and the commencement of the sensory trunk as far as the ganglion. It is probable, however, that in a certain number of cases, the atrophic stage may be preceded by a process of genuine inflammation, and that this inflammation is centripetally produced in consequence of inflammations of peripheral portions of the nerve. The considerations which make this probable are chiefly derived from the analysis of cases in which a more or less chronic, but severe, visceral disorder has been followed by so-called reflex paralysis, but in which neuralgic phenomena, have been conspicuous. In reference to this subject I recommend to the reader's attention the very interesting paper on "Reflex Paralyses" by Prof. Leyden, of Konigsberg.[28] He is immediately commenting upon a case in which dysenteric affection of the bowel were followed by the symptoms of myelitis, attended with febrile exacerbations, and also with severe pains in the region of the sacrum, in the course of the dorsal intercostal nerves of the right side, and in the knees, and semi-paralytic weakness of the lower extremities, and with pains between the shoulder-blades and the left arm. Leyden discusses the doctrine of reflex paralyses in general, starting from the cases of urinary paraplegia brought forward by Stanley, in 1835, and tracing the growth of opinion through the phases represented by Graves, Henoch, and Romberg, by Valentine and Hasse, then by Pfuger, and other professors of the inhibitory doctrine; by Brown-Sequard (in his well-known, and now very generally discredited, theory of spasm of the vessels in the nervous centres), by Jaccoud in the "Erschopfung" (exhaustion) theory, down to the more careful and reliable researches of Levisson on the temporary reflected paralyses induced by experimental squeezing of the kidney or uterus of animals; and then gives the history of the more recent doctrine of a positive material change in the cord centripetally introduced. Gull[29] (1856) may be said to have inaugurated the new doctrine of a morbid process transmitted along the pelvic nerves to the cord, and causing material changes there. Remak,[30] on the other hand, suggested a material change operating in the opposite direction; _a neuritis descendens_, starting in the very nerves (within the pelvis) which showed the paralysis in the extremities. The symptoms are supposed by him to be distinctive, inasmuch as there is both violent pain in the nerves of the soles of the feet, and also tenderness of the same. On the other hand, Remak said that myelitis, with neuritis, might be the origin of paraplegia and simultaneous palsy of bladder and rectum. The theory of neuritis