Dr. Ireland, writing on the double brain (op. cit.), quotes largely from Dr. Edgar Berillon's book. † This author certainly has the courage of his convictions, for, after giving many examples of the double-brain action, he records experiments which satisfy him that through the agency of hypnotism we can induce this double action. For instance, he will speak into the right ear of a subject in a profound state of hypnosis, and describe to her an amusing scene at a theatre; then into the other ear he will pour some tragic tale. The right side of the face will express pleasurable feelings, whereas the left side will, at the same time, wear a look of grief or terror. Dr. Berillon defies anyone in an ordinary state of health, or even in hysteria, thus to produce the simultaneous expression of a double set of emotions. He makes the following inductions:' 1. That hypnotism can suppress the psychical motor and sensory activity of one hemisphere of the brain. 2. That it can give to each hemisphere a different degree of activity. 3. That, the two hemispheres having an equal degree of activity, we can create for them at the same time manifestations varying in their seat, their nature, and their character.'

* Moll (op. cit., pp. 192, 193) is of opinion that such obedience generally implies a slight degree of hypnosis, induced by the mere command in a susceptible subject.

† 'Hypnotisme Experimental, la Dualite Cerebrale, et I'lndepen-dence Fonctionnel des deux Hemispheres Cerebraux,' Paris, 18184.

That a transference of functional activity from one side of the brain to the other may sometimes be effected by hypnotism seems to be shown by the case of Louis V------ (described on p. 99). This subject was easily hypnotized, and in the hypnotic state would lose the right hemiplegia from which he was suffering, and walk quite naturally. When he was hypnotized, both his eyes were shut, as in natural sleep; and if either of them was forcibly opened, the corresponding side of his body became cataleptic, while if both were opened the whole body took on this condition. If the right eye was opened while he was talking or reciting in the hypnotic state, he not only became cataleptic on the right side, but also aphasic, and the physician in attendance, Dr. Jules Voisin, came to the conclusion that this action produced an inhibitory effect on the left hemisphere, and consequently and inclusively on the normal centre of speech. When the eye was again closed, he took up his speaking or reciting where he had left off. The opening of his left eye in his ' first state ' had no effect on his speech; but in his ' second state,' during which his words and mode of expression were extremely childish, opening the left eye stopped speech, whereas opening the right eye produced no effect.

This, according to Voisin's theory, supported to a certain extent by Burot and Bourru, showed that the speech centre had shifted sides. In his ' first state ' Louis V-----used chiefly the left hemisphere of his brain, and in his 'second state' the right hemisphere, which, being less educated than the other, accounted for the imperfect character of the speech produced during its preponderance. Dr. W. Ireland, * in his interesting volume of essays dealing with abnormal mental conditions, gives some curious examples of double consciousness occurring in the course of disease and from poisoning. He refers to hashish-eaters being sometimes conscious of a double individuality, and quotes the well-known case of a drunken porter who, when sober, used entirely to forget where he had left his parcels, and remembered it only when he was again intoxicated - that is, when the brain was again in the same specific state which it had been in when he committed the action. Dr. Ireland also mentions the sensation of double personality sometimes experienced by a person suffering from severe illness, who has appeared to himself as two different individuals, one of whom suffered, while the other looked on and pitied him.

* 'The Blot on the Brain,' Edinburgh, 1885.

Draper, in his work on Physiology, refers to this point, and remarks that one never experiences three consecutive trains of thought, for the very good reason that our brains possess only two hemispheres. He considers that the two sides may sometimes act independently, and even in-harmoniously, and thinks that double cerebration may be thus explained. Thus we may follow out a train of thought while giving a fair amount of attention to an address or sermon, or we may even be able, like Mr. Bark-worth, of the Society for Psychical Research, to carry on an ordinary conversation while adding up a double column of figures. Of course the theory of a double action of the cerebral hemispheres need not be invoked to explain such everyday occurrences as being able to play the violin or piano whilst carrying on a conversation-. Practised musicians can, we know, play difficult music while engaged in conversation, just as artists are able to talk to their sitters while painting them. But we need not invoke the theory of dual brain action to explain this, any more than we require it to explain how it is a sempstress can ply her needle and sing the while.

In these cases continued practice has made the special movements of eye and hand automatic, and there is no question of employing the functions of higher cerebration. When the artist comes to a difficult passage or piece of work, he is seen to become silent and to devote all his faculties to its elaboration. The associated group of centres require the control and leadership of the highest nervous arrangements.

The brain is, of course, a double organ, anatomically and physiologically; and though in normal life the two hemispheres are so functionally associated that they act as one, such cases as those I have cited seem to show what most observers are agreed in concluding, that under certain conditions the partnership may be dissolved, and one side may act independently of the other. In some cases of insanity the patient has been observed to ask questions and reply to them, as in two different capacities, and Ireland supposes that in such instances the two hemispheres are acting alternately. He suggests that the existence of such conditions may prove a key to the explanation of many cases of 'spirit-possession' and hallucination.

The left hemisphere is much more used than the right, and in general is proportionately more developed, though in left-handed persons the reverse is said to be the case. But although we may ordinarily use only one half of our brain for certian actions, we can sometimes, in case of necessity, educate the neglected half to act when the other is injured. We may thus explain those curious instances in which, after an illness, previous education is forgotten, and the patient has laboriously to learn everything over again - to re-educate his brain, or rather to educate that portion of it which hitherto has been comparatively unused. Hypnotic suggestion, circumspectly used, might doubtless afford valuable assistance in such brain education.

The dissociation of the two sides of the brain, and the transference of preponderating influence from one to the other, certainly seems to afford a plausible explanation of many of the phenomena of advanced hypnosis. But it is not so easy to attribute to this dissociation and transference the therapeutic and other effects observable in the minor degrees of hypnotic influence with which the practitioners of the Nancy school are satisfied. Physiological theories change as knowledge increases, and when they are proved to be erroneous they are apt to drag down in their fall the practice which has been founded upon them. Therefore, while avoiding mere empiricism, it is safer not to depend too much on any as yet unverified theory of hypnotic suggestion. Within the next few years a flood of light will probably be thrown upon this subject, if, as we hope, the formation of a medical society for the study of suggestive therapeutics leads to the interchanging of ideas and experiences among practical men.