wish-fulfilment and the like, can color the content of the lapse. They may, quite obviously and consciously, but it does not seem that, when there is no appearance or consciousness of such mechanism, the present psychoanalytic method is suitable for the valid demonstration of one. The whole question of these and the Symptomhandlungen at large depends upon the crucial test of whether any unconscious factors beyond those of distraction can be demonstrated that are not equally present where no Fehlhandlung occurs.

Many factors contribute to render the teachings of psychoanalysis peculiarly liable to favorably or unfavorably prejudiced judgment. The subject seems unfortunately apt in turning either a man's stomach or his head. Being usually concerned with matters that involve considerable intensities of personal feeling, objective judgment of results would not be of the easiest, even were the psychoanalytic method itself less open to criticism on this score. How much of Freud one to-day believes is bound to be largely a matter of feeling, because the data of the method are so little susceptible of valuation upon any other basis. Whatever of these theories be true or false, there seem to have been but scattered attempts to submit them to the test of experiential conditions.

This question of the validity of the psychoanalytic method for demonstrating certain mental mechanisms is, of course, but a part of the larger questions of the role of psychogenic factors in mental disturbances. So far as we know there are no mental experiences of a specifically pathological nature, but mentally pathological reactions to any given situation are determined by the individual's constitution or immediate powers of resistance. The experiential factor in our mental life is an essential determinant of the content of the mental reactions. But whether those reactions are of a healthy or pathological character, depends far less upon external situations than upon the organism which has to adjust itself to them. The content of the maladjustment is of chief importance for the light it may throw upon the fundamental conditions that have permitted it to take place.

The tremendous role of sexuality in the Freudian theo

ries is largely derived in but doubtful ways, and the exact character of its relation to the psychogenesis of various pathological conditions must also be regarded as largely uncertain. The vita sexualis is indeed the touchstone of mental stability; but it does not follow that the failure of sexual adaptation is an essential cause, or, in fact, other than a frequent or inevitable symptom of neurotic disturbance. Some psychoanalysts are fond of accounting for the non-acceptance of their doctrines on the ground of sexual resistances in their opponents, and lay great stress on conventional prudery and suppression as a bar to the progress of their teachings. But it must not be lost sight of that there is a type of personality that would be attracted to psychoanalysis by the very prominence it gives to sexual factors, its facilities for mental mixoscopia perhaps affording to the sexual feelings a not disagreeable stimulation of the safer and cheaper sort. There may be applicability in both of these assertions, but they scarcely touch the question at issue. The truth or falsehood of a proposition, judged by such criteria as scientific progress has been able to build up, is a more important question than whether certain individuals accept or reject it on other grounds. The most rigid control of its observations may not enable psychoanalysis to win the respect of all its opponents; but this does not absolve those responsible from the duty of making an adequate effort to deserve it.

I

THE EVOLUTION OF SLEEP AND HYPNOSIS

BY ISADOR H. CORIAT, M.D.,

Boston, Mass.

N a former contribution* there was discussed the nature of sleep, in which it was shown that sleep was due to

an absence of those peripheral stimuli from the receptor organs which normally keep the brain in activity. It was furthermore demonstrated that the motionless states into which animals could be suddenly thrown were not sleep but a form of cerebral inhibition, strongly allied to hypnosis, if, indeed, not identical with it. These experiments on the nature of sleep and hypnosis suggested several other directions to which inquiry might be directed namely,

1. How did sleep and hypnosis evolve?

2. What is the biological necessity for sleep?

Although it has been noted that primitive, moving unicellular organisms when observed for hours at a time, were unceasingly active and showed no motionless states, yet sleep must have arisen at some stage of evolution from these primitive organisms. Presumably those organisms survived which possessed these motionless states to their greatest extent, and from these motionless states could probably be traced the phylogenetic origin of sleep. In the higher animals, however, that is, in those possessing a complex nervous system, these motionless states, as demonstrated by my experiments, were not sleep but a form of cerebral inhibition, a genuine hypnosis. Furthermore, the animals experimented upon possessed genuine spontaneous sleep states, whereas the motionless states induced in them were artificial and experimental.

In the lower organisms these motionless states are not intelligent reactions, but probably blind mechanisms, and we must therefore not allow the interpretation of such phenomena to lead us into anthropomorphism. Neither can they be said to arise from fatigue, because such states

*Isador H. Coriat. The Nature of Sleep. JOURNAL ABNORMAL PSYCHOLOGY, Vol. VI, No. 5, pp. 329-368.

may be observed in organisms which have not been subjected to stimuli that would lead to fatigue. Lower organisms, however, are very sensitive to light, but whether this influence to light is a chemical or a mechanical phenomenon cannot be discussed at present. For instance, many motile forms collect in regions of a given light intensity, some orient themselves towards the source of light and others away from it, into shadows or where the light is diminished.* These light reactions may be decidedly rhythmic in character and because they usually result from sudden changes in the intensity of light, they seem compulsory and mechanical. It has been found, for instance, that a sudden increase in the intensity of light will cause restlessness in earth worms and fresh water planarians. Diminution of the intensity of light inhibits these restless reactions and causes the creature to come to rest, or if such a creature goes from a light area to a dark one its activity becomes reduced to a minimum, it becomes motionless and seems to fall asleep.

It seems probable that out of these periods of immobility and rest sleep arose. Light is a distance receptor and the activity of these organisms ceased when these particular receptors failed to throw its nerve elements into activity. The same mechanism probably takes place in the sleep of man and the higher animals from the inhibition of distance receptors. If sleep is an instinct, it was not so in the primitive organisms, but in these creatures, it was a tropism, a mechanical or chemical necessity for repose under conditions where light was absent. From this tropism-like reaction, sleep arose, a veritable impulse of living matter to higher and higher rhythmic activities, motility on the one hand, with its freedom of action and the consequent development of the nervous system, periodic immobility on the other, in the effort to protect this nervous system from the pernicious effects of over-activity. Thus those organisms which showed these rhythmic reactions of immobility and

*On the various tropisms and the reactions of organisms to light, and the interpretation of these phenomena from the standpoint of comparative psychology, see the publications of Loeb, Piéron, Bohn, Jennings, Verworn, Claparede, and Mast.

repair were those which survived in the biological struggle for existence.

Let us investigate these complex reactions to light more closely. Sometimes instead of attaining a definite axial position or orientation to the source of stimulation, the organism as a whole will move from light to shadow or vice versa. Whether or not these reactions are adaptive or mere mechanical automatisms is one of the most important questions of comparative psychology. Probably the phenomenon, at least in the more primitive organisms, is not psychic, the light in these cases acting as a mere directive stimulus. We are dealing here with a process variously termed heliotropism or phototaxis. The fact that in brainless planarians can be demonstrated the same sensitiveness to light, but that the reaction time to arrive at immobility is longer, speaks in favor of the mechanistic hypothesis.

Histological investigations on planaria and earth worms seem to indicate that the photo-sensitive elements are distributed over the body surface. That the reaction to light is a mechanical or a chemical response without the involvement of consciousness or perception, a mere mechanism, is demonstrated by two facts; first, that brainless organisms show the same reaction, and secondly, blinded organisms become motionless when the light intensity is suddenly reduced, or what amounts to the same thing, when shadows are suddenly thrown over the bodies of the creatures. These reactions to shadows seem to be defense reactions, because a shadow would naturally herald the approach of an enemy. Then the organism becomes motionless, a condition under which it would be less likely to be perceived. Analogous conditions are sometimes found in the higher animals, namely, simulation of death, but here the defense reaction is intellectual and not mechanistic. Thus these latter reactions are in a general way adaptive and serve a purpose in not only protecting the creature from external influences, but likewise have a reparative action.

Sleep, therefore, in these lower organisms seems a mere rest state, a negative heliotropic reaction, because of the poverty of the creature in receptor organs. As the animal