The nerve terminations, from their outpost position, receive the first shock; but what part do they play? It is known that the nerves of the deep organs and the filaments of the great sympathetic have no specially constructed terminations. The nerves of special sense, on the contrary,—vision, hearing, smell, and taste,—possess special peripheral apparatus (retina, organ of Corti, etc.) of very complex anatomy; it is known that their _rôle_ is specially sensorial; they are above all instruments of knowledge, seldom directly of pain or pleasure. So that the question of nerve terminations in relation to pain may chiefly be confined to the nerves of the tactile apparatus, taking the word in its largest sense. The extreme difficulty of isolating the purely peripheral impression from that which reaches the nerve itself renders almost insoluble the question as to the part played by these peripheral apparatus. Beaunis,[12] relying on the cases of localised anæsthesia in which the patient no longer feels pain but still perceives contact, thinks that analgesia would reach the nerves before acting on their terminations, shut up in more or less resistant capsules. ----- Footnote 12: _Sensations internes_, Chap. xx., may be read for details on this point. ----- Are there special nerves for the transmission of pain? Goldscheider, well known for his researches on cold and heat points on the skin, at first maintained that there are.[13] According to him, the pain-bearing nerve filaments are interlaced with the sensorial nerves, more numerously with the nerves of general sensation (touch, heat, cold), less numerously with those of special sense. If the existence of these special pain nerves were well established, it would have as great an importance for our subject as the discoveries of Sachs and others, on the nervous filaments peculiar to the muscles, have had for the study of the kinæsthetic sense. But this physiologist has since repudiated his first assertion, and maintained that it was misunderstood; he admits pain points (points sensible to pain), but not a specific organ for pain nor special nerves to transmit it.[14] Frey, on the other hand, professes to have proved experimentally both pain nerves and appropriate terminal organs. His observations have been rejected as inaccurate. At the present time there is nothing to establish the existence of pain nerves, and most authors have given strong reasons against the probability of such a discovery. Rejecting this hypothesis, we may admit that an impression of pain, like any other impression, is transmitted by the nerves of general or special sensibility. When it has entered the spinal cord at the posterior roots, the road it follows to reach the higher centres has given rise to much investigation and discussion. According to Schiff, transmission takes place through the grey substance, tactile impressions passing by the posterior fibres; there would thus be two distinct paths, one