The heart, again, affords one of the best examples of the close association of neuro-regulatory arrangements and their action upon each other. If the heart is removed from a cold-blooded animal, it will continue to contract rhythmically owing to its containing within itself ganglia derived from the sympathetic system. But these ganglia have not all the same functions. The principal ones, three in number, are those of Bidder, Remak, and Lud-wig. The two former appear to be excitor centres, while the latter is a moderating or inhibitory centre. This is well shown by experiment. Let the heart be cut into two unequal portions, one consisting of the right ventricle (with the ganglion of Remak), and the other of the two auricles and the left ventricle (containing Ludwig's and Bidder's ganglia), the first portion will continue to beat, but the second will remain quiet. Let this second portion be again divided, and the auricles (containing in their septum Ludwig's ganglion) will be found to remain quiet, while the ventricle will recommence beating.

Ludwig's ganglion has thus proved strong enough to counteract one excitor ganglionic centre, but not sufficiently strong to control two (Kuss's ' Lectures on Physiology,' edited by Amory, p. 169).

It is probable, as Brown-Sequard says, that all sensory and sensorial nerves are capable of determining inhibition, and the study of hypnotism affords a valuable confirmation of this theory. The highest centres may be inhibited by acting on several sensory areas and tracts, and the position of these seems to vary in different individuals. Gentle friction, for instance, of the forehead will in many persons speedily determine cortical inhibition and hypnosis, and some writers have even described inhibitory or hypnogenic zones. * The phenomena of zonar epilepsy afford a useful analogy here. Slight pressure on the ovaries will in many of these cases start an epileptiform fit - i.e., will convey a strong inhibitory impulse to the cortex - and the highest layer will be inhibited with corresponding overaction from dynamogenesis of the lower. Conversely we find that strong pressure over the ovaries will cut short an attack which has begun, thus showing the close relationship between the neuro-regulatory forces. But though it is probable that hypnogenic zones may sometimes exist spontaneously, we must be careful to avoid confusing them with what we may call habit zones.

Nerve habits are readily set up, especially in hysterical subjects, and an artificial hypnogenic zone is easily called into being by suggestion. One would only have to tell a sensitive person that pressure on his right temple would determine the hypnotic state, and we should either at once, or in a short time, find that this action would become a hypnogenic agent.

* Professor Pitres gives an exhaustive account of these zones in his important work. His position and experience demand our acceptance of the facts he records, but some of them - e.g., the occurrence of ideogenic zones in hysterical subjects, pressure upon which give rise to various emotions and sensations according to the areas stimulated - make considerable demands on our imagination. It is a matter for regret that, like Charcot, he seems to have confined his researches in hypnotism almost entirely to hysterical subjects, as experiments on healthy persons give much more satisfactory and trustworthy results. Bernheim denies the occurrence of hypnogenic zones, except as a result of conscious or unconscious suggestion on the part of the operator; but Pitres gives evidence that it is impossible to ignore, and it is, I think, best to admit that these zones are of spontaneous origin in a few exceptional cases, just as Charcot's three stages may sometimes occur without suggestion. According to Pitres, the zones must be carefully looked for, as they are usually confined to a small area. There may be only one discoverable, or the number may mount up to fifteen or more.

He describes (with diagrams) the case of one hysterical young woman having ten hypnogenic zones; two of these were situated in the middle line, one at the root of the nose, and the other on the vertex, and eight on the left side, viz., on the malar process, the superior body of the clavicle, mammary region, bend of the elbow, upper and external part of the thigh, knee, external malleolus, and internal malleolus.

The result of touching any of these zones was that the girl fell at once into the lethargic stage of hypnosis (Charcot), and remained in it until she awoke spontaneously, or was awakened by touching other areas which acted as waking (hypno-phrenetic) zones. The danger and inconvenience arising from the existence of these zones, whether natural or acquired, is demonstrated by many cases referred to by Dr. Pitres, and if they are found to exist, hypnotic suggestion should be employed to remove them. A physician once told me that he accidentally touched one of Charcot's patients on the elbow, and that she at once passed into a state of catalepsy; and in Luys's clinique I have seen patients who are equally subject to being in a moment reduced to a stage of helplessness, and perhaps unconsciousness. Such development of hysterical phenomena, whether practised in the wards of a hospital or on a public platform, constitutes in my mind a grave abuse of hypnotism. Instead of developing the morbid hypersus-ceptibility of hysterical subjects by hypnotic education, it appears to me much more commendable to correct and cure it ('Hysterie et Hypnotisme,' vol. ii., chap. 44).

At Amsterdam Drs. Van Renterghem and Van Eeden used sometimes to awaken their patients by touching the tips of their noses, and this contact was at once sufficient to end the sleep, no matter how deep it might be. An artificial dynamogenic zone was created. The effects of nerve habit are, of course, visible all around us. The paterfamilias who has only to take up the paper after dinner and sit in his accustomed chair by the fire, in order to almost immediately fall into a doze, is a familiar example of this condition; only a little less marked than that which we sometimes set up by hypnotism, when we give the patient a piece of paper, and tell him that on looking at it he will at once feel sleepy and fall into a sound sleep. The sleep of the business man over his accustomed paper is, I believe, frequently of the hypnotic type. Though it commonly lasts only a few minutes, such sleepers have frequently told me that it refreshes them more than their night's rest; it is the rest of simple inhibition. Many great generals, like Napoleon, have been able to snatch sleep of this type at any time and to awake from it not only refreshed but inspired.

Ordinary hypnosis is not alone in producing this sudden or rapid change - ' a few moments of sleep' - a mere blur across the field of consciousness, will sometimes bring a renovation which hours of lying down in darkness and silence would not yield. Some subtle adjustment of nervous energy to organic needs takes place, and the whole aspect of the case changes (Myers). Brown-Sequard points out that anaemia is a predisposing cause of inhibition, and it has been the experience of all observers in regard to hypnotism that anaemic persons are often the best subjects.