Particular interest attaches to the question of hypnosis in animals, It is well known that a number of animals can be put into a condition which corresponds at least in many external earmarks to that of hypnosis in human beings. Such conditions may for instance be induced in the common crawfish and also in mammals. The means of bringing animals into the hypnotic state is to retain them in uncomfortable positions. The hypnosis of animals (Pryor) has been traced to terror and use has been made of the term terror rigor (Schreckstarre) or cataplexy. Forel, not without reason, raises the objection that precisely the tamest animals are the easiest to hypnotize. He is inclined to speak of true suggestion. No doubt a psychic factor is present in hypnoses of animals. Now Verworn has shown that the reflexes produced by retaining the animal in unaccustomed and inconvenient situations are tonic recumbency reflexes. He is wrong, to be sure, when he infers that animal hypnosis is therefore without a psychological phase, for animal hypnosis may indeed depend on the one hand on tonic recumbency reflexes and yet have, on the other hand, a psychological foundation. " Psychological" and " physical" are by no means opposites, and we must again emphasize, with Bleuler, that it is necessary to say: " Physical and psychical" and not " physical or psychical." It is worthy of note that according to Mangold, who has summarized all the literature on this point, hypnosis may be brought about even in birds and mammals having no cerebrum. Spiegel and Goldblom have recently gone so far as to show that the phenomena of hypnosis may be brought about if only the center of the posture reflexes, the red nucleus, has still been retained. In other words, as long as the animal is capable of any changes of posture at all, it may be induced by the procedures bringing about animal hypnosis to refrain from carrying out these alterations of posture. Now we must apply even to the experimental results in the cases of animals, the general point of view that the removal of a section of the brain may under certain circumstances cause functions to live again in more primitive sections of the brain which in their normal functioning had not been utilized or at least not to the same extent. In other words, if, after the removal of a certain section of the brain a function suffers no alteration, such experiments do not show that the removed section of the brain has no importance for this function. But it is none the less noteworthy that the hypnosis of animals points to the fact that much of what we are otherwise accustomed to ascribing to hypnosis takes place in primitive motor centers.

Still greater are the difficulties encountered in recognizing hypnosis in invertebrate animals. As a fundamental principle we may distinguish two types, namely a hypotonic and a hypertonic type, in other words, the same types that are found in the hypnosis of human beings, particularly noteworthy is the following observation, communicated by Mangold (according to Heymans). In the ugly weasel spiders of the species Galeodes Kaspius turcestanus, the female attempts to devour the wooing males; the female will not permit the performance of the sexual act unless the male succeeds in imbedding his forcipated jaws in a certain spot of her abdomen; the hypnotic condition of the female may be imitated in the laboratory by seizing the above mentioned spot of the female with the pincers though, characteristically enough, this experiment can only be performed in the mating season. Mangold himself is inclined to consider animal hypnosis as a device in the service of sexual instincts, and it may indeed be surmised that hypnosis and a condition resembling hypnosis always ensue in the course of sexual relations, when the resistance of the female begins to be excessive and seriously to endanger the actual performance of the sexual act. Mangold distinguishes between hypnosis and the reflexes of simulated death (trance) which are rather calculated to serve to protect the specific individual. But we must recall that hypnosis undoubtedly has a connection with sleep and that these connections may hardly be disposed of by reference to sexuality alone. Furthermore, there must be certain bridges between sleep and trance, for the examples communicated by Zell showing that sleep ensues in the animal world when the animal would incur danger by continuing its motions, seem to constitute an excellent formulation of a portion of the problems. Certain relations will therefore have to be assumed nevertheless between sleep on the one hand and trance reflexes and hypnosis on the other hand. Of course, in order to find an analogy to the social-psychological side in animal hypnosis, more thorough investigations will still have to be made in order to determine the conduct of animals when not under human influence. Freud, no doubt rightly, points out in Group Psychology and the Analysis of the Ego that we must take into consideration, in interpreting the hypnosis, the fact that the leader must not be obliged to reckon with a continuous resistance. In animals which live in communities, also, the superiority of the leader of the tribe may be valuable only if he need not give evidence of his authority on every new occasion. Schjelderup-Ebbe has shown in the case of birds that relations of superiority and subordination are found in the animal world. " Intimidation " is often a decisive factor, and once an animal has become a tyrant over the others, this condition will continue to exist without special exertion of effort even though the balance of power be by no means in favor of the tyrant. A consideration of hypnosis in animals may, to be sure, not afford us a final answer to the question of human hypnosis, but it does raise a number of important problems.

Not long ago Tromner tabulated the differences between animal hypnosis, which he designates as catalepsy, and human hypnosis. We are giving this tabulation below and commenting on it because we believe that a controversy between us and this distinguished worker will enable us to present our own view more clearly:

Note on 1. Shock proceeds in some kind of relation with psychic experiences. In human beings also there exists a sort of hypnosis through domination and terror. It is true that in the production of human hypnosis the material of conception is of particular importance, but we have again and again pointed out that there are a number of phenomena in hypnosis which are independent of the activity of the imagination.

Note on 2. Animal hypnoses may also last for some time. As a principle it may be stated that human hypnosis likewise ends in a shaking off of the hypnosis, not to mention the light degrees of human hypnosis; but a spontaneous awakening ensues after a more or less protracted period even in profound hypnosis.

Note on 3. Whether the motor restraint in animals is exclusively motor in nature, whether it is not connected with psychic changes, is an open question. We have already pointed out that in the hypnosis of humans there are times when only motor restraints control the picture.

Note on 4. Hartmann and Schilder have also succeeded in obtaining hypnotic phenomena in the case of insane paralytics, as will be mentioned later.

Note on 6. Even though we are not in the habit of speaking of hypnosis in the case of very young children we must nevertheless point out that the procedures by means of which a crying infant is pacified, namely, rhythmically repeated stroking, gentle admonition, etc., the procedures that induce sleep in the infant, are the same as those used in bringing about hypnosis. We entirely agree with Tromner when he says that the hypnosis of humans and the hypnosis of animals must necessarily be of different nature owing to the difference in their brain construction. Yet, the common elements are so significant that we must assume a certain identity in principle. This identity is recognized even by Tromner to the extent of his considering hypnotic catalepsy and catalepsy in animals as of similar nature.

Let us now begin our discussions of the physiology of hypnosis with a discussion of catalepsy and of the motor phenomena of the hypnotized. One of the present authors has already pointed out(*) that the cataleptic phenomena of hypnosis present a fundamental similarity with those phenomena afforded by the lesion of the striopallidary system. The. catalepsy encountered in certain cases of encephalitis epidemica (compare Gerstmann and Schilder on this subject) shows very great similarities with the catalepsy of the hypnotized, which, as is well known, is characterized in general by the fact that the posture is maintained with as slight an expenditure of muscular contraction as possible.

(*) " Das Wesen der Hypnose," Seele und Leben.

The expression striopallidal system is incorrect to the extent that we are as yet not in a position to estimate the importance accruing to the striopallidal system as such in this reaction, or the importance of the substantia nigra, or of the cerebellar systems. If one would undertake to make a thorough study of the problem of catalepsy, one must not forget that there are essentially two components of catalepsy involved. On the one hand, there is (akinesia) a defective locomotion urge, or a defective locomotion will; on the other hand, there is the muscular tonus which is necessary to maintain the communicated passive position. The doctrine of the striopallidal origin of hypnotic catalepsy has recently also been advocated by Leyser.

One of the present authors has in part repeatedly emphasized, in his work together with Gerstmann, the fact that such modes of viewing the question are of fundamental importance for the theory of the muscle tonus and of the striopallidal system. In this case, on the one hand, the considerable susceptibility of disturbance of striopallidal motility by psychic factors must be stressed, and on the other hand the muscular phenomena consequent upon purely psychic adjustments, with purely psychic condition reflexes. Thus, Kauders has described images of psychogenically conditioned disturbances of motility which correspond to far-reaching parkinsonisms.¹ We cannot lay sufficient stress on the questions thus arising, which begin with the fundamental investigations of C. and O. Vogt and Kleist. The important continuations of these suggestions by F. H. Lewy and Homburger promising to throw considerable light on the question of motor experiences and behavior in general, even in normal persons. Again and again stress must be laid on the close connection between psychic experience, on the one hand, and the motor type and motor expression, on the other hand, which has its center in the striopallidal system.

But the physiology of the attitudes and of the motility of the hypnotized is by no means exhausted with the considerations advanced above. Goldstein and Riese were the first to point out that the attitude and posture reflexes of Magnus and DeKleijn can be detected also in normal man. As Goldstein and Zingerle have emphasized, there are cases in which automatic movement (Ablaufe) follow upon an alteration in the posture of the head, and prevent the individual from attaining repose. Hoff and Schilder were able to confirm this. Simultaneously with the proceeding of these involuntary movements (Automatose, Zingerle) remarkable changes ensue in the state of consciousness. Between these movements and the state of consciousness there are connections whose nature has not yet been cleared up. We must assume that we are dealing with posture reflexes and their consequences, whose center is found in the red nucleus, at least in animals. Now, we have called attention above to Spiegel's investigations, which show that hypnosis cuts off the posture reflexes. Accordingly we may expect that the posture reflexes suffer a similar change in human hypnosis. This assumption is confirmed by experience, at least to the extent—as shown by Levinger—that the posture reflexes in hypnosis are actually considerably diminished in hypnosis, a statement that has been fully confirmed by Hoff and Schilder. We may state in explanation of these conditions that the muscular tension during hypnotic sleep is very slight and that a certain amount of muscular tension seems necessary in order to produce posture reflexes in general. On the other hand, however, it would be wrong to underestimate the akinetic factor in hypnosis. We thus attain the view that the stimulus to motion in hypnosis has been switched off also in those strata which serve for the production of posture reflexes, or automatosis. Here again we may point out that in the greater number of akinetic encephalitics position and posture reflexes are also reduced or absent. We thus find that we are already in a position, in view of the material now available, to form certain ideas on the physiology of motility in hypnosis. Let us here recall also that it will be best possible for us to understand the motor stimulus phenomena observed in hypnosis, the hysteriform convulsive twitching, even the occasional hysterical attacks, if we bear in hind the removal of the inhibitions over primitive motility. The thought that so-called psychogenic disturbances of motility may here be conceived as physiological goes back to Meynert, but has obtained a more precise formulation only since the investigatoins of Leipman, Kleist, C. and O. Vogt, Gerstmann and Schilder, and Leyser.

(*) A girl of fifteen is at present under my observation and treatment for a condition of hypertonia of her right upper and lower extremities and is suggestive of a decided parkinsonism, though she was considered for a long time to be a case of hysteria. Hypnotic suggestion has very decidedly influenced her condition for the better though the hypertonic attitude still remains.—Trans.

Above we have already declined to dwell on the details of the question of how the primitive motility is interrelated with the more highly developed motility, and how the two cooperate. Also, we must mention the problem involved in the fact that the primitive motility is closely related with the vasovegetative system. We refer thereader to F. H. Lewy. At any rate, we maintain our position that the functioning of motor apparatus of comparatively primitive structure is of importance for the motor phenomena of hypnosis, the apparatus being located in the midbrain, interbrain, and hindbrain.

We have already spoken of an influencing of the sleep center. There is no doubt that the latter is situated in the neighborhood of the third ventricle, as we have stated above. But the neighborhood of the third ventricle happens to be also the location of the central station of the vasovegetative functions in general. Here lie the centers for the regulation of temperature, for the bladder, saliva, respiration, sexuality, metabolism, and the glands of internal secretion. As for the individual data, we refer to the article by Muller and Greving which appeared recently in the Med. Kl. Muller and Greving point out that stimulations of the sensory neurones, proceeding from the optic thalamus, pass over to the vegetative system, that the pupils dilate owing to the pain, and that saliva and perspiration are secreted as a result. The stimulus therefore evidently is conducted to the interbrain. We now quote literally the statements of these authors: " Thus, we know that Karplus and Kreidle succeeded in obtaining a protrusion of the bulbus, a dilation of the pupils and the eyelids, increased lachrimal, salivary, and perspiratory secretion, by stimulating the subthalamic region. Aschner and Leschke secured polyuria, with unconquerable thirst (diabetes insipidus) and temporary glycosuria, by pricking the floor of the third ventricle and avoiding the hypophysis. Jakobi and Roemer were able to obtain an increase of bodily temperature by introducing carbolic acid or mercury into the infundibulum. Isenschmidt and Krehl excluded the regulation of the bodily temperature by a frontal incision behind the optic thalamus. Erdheim observed, after diseases of the infundibulum, though the hypophysis remain completely intact, an atrophy of the sexual apparatus and a lowering of the sexual desire and sexual power, a cessation of menstruation, and a retrogression of the secondary sexual traits, together with a marked increase in adipose tissue all over the body (dystrophia adiposogenitalis. In some diseases of the walls of the third ventricle we obtain only disturbances of the sexual apparatus, or only obesity. Many grounds speak for the assumption that the superior center for sexual and procreative activity is to be found in the corpora mamillaria. ... It seems reasonable to assume that the walls of the third ventricle contain the spot which regulates the metabolic processes of the body. Not only from the ensuing of obesity after injuries and the formation of scars in the infundibulum, but also from the enhanced combustion processes in fevers, which are stimulated from the temperature center, and from the serious conditions of wasting, such as appear in many cases of chronic hydrocephalis of the third ventricle, particularly in connection with meningitis, cerebrospinalis epidemica. Enlargement of the epiphysis, which also belongs to the interbrain, not only result in pathologically premature development of the sexual organs and the sexual desire, but also— probably by stimulations of the ventrical walls—to abnormal appetite, to polyphagia. Thus we find that not only thirst, but also hunger, may be produced by the vital centers in the central gray matter. Some investigators place the vasomotor center in the corpus hypothalamicum under the optic thalamus, in the corpus Luysii. From this region, according to certain authors (Liechtenstern), the subcortical stimuli to the bladder innervation take their origin. The innervation centers for the sebaceous glands must also be sought medically from the globus pallidus." We must also pay close attention to the report of Dresel and the book of F. H. Lewy, in which there is a discussion of the fundamentally important question of whether the vegetative apparatus is constructed in a number of levels. Dresel and F. H. Lewy assume that there is a superior level above the vegetative centers in the medulla oblongata which must be sought in the environment of the third ventricle in the nucleus periventricularis and in the centers of the interbrain region. Centers situated in the striopallidal system would then appear to take care of the delicate adjustments. The authors follow out these thoughts in great detail with regard to the regulation of sugar and temperature control. Thus, they hold accountable in diabetes mellitus, a spot in the pallidum, for the disturbances of sugar regulation, a view which is, however, contradicted by Bielschowsky. Whatever be our judgment of these things as far as details are concerned, there is no doubt that there is a succession of levels of the vasovegetative apparatus. It may also be assumed with certainty that mechanisms are situated in the midbrain which regulate the production of the endocrine secretions. In this connection the question as to the centers for sexuality is of particular importance. It has been already settled that centers on the floor of the midbrain are of essential importance in the production of distrophia adiposogenital. It is probable that the hypophysis and the interbrain have an influence here also. As for details, we refer to the textbooks on internal secretions by Biedl and Weil. Similar considerations will also be of importance, probablv. in the case of diabetes insipidus. The posterior lobe of the hypophysis and the vegetative centers at the floor of the interbrain are the organs that are of importance in this connection. We may therefore say that the vegetative functions in the interbrain have a central localization, and that it is from this central point that the vegetative life is supervised. This central station has control of a more primitive center situated in the medulla oblongata, but is probably also connected with stations of higher level. There is no doubt that the functions of the cerebral cortex must be extremely susceptible to action proceeding from these centers, as Reichhardt especially has repeatedly pointed out. Every experience of psychic type connected with the cerebral cortex accompanies in some manner the functions of the vegetative system. The latter vibrates together with the function of the cortex. Now we have every reason to assume that the vasovegetative system has preserved a greater degree of plasticity than the cortical function. Its function appears to have been differentiated in less degrees. Kraus speaks of a vegetative Tiefenpersonlichkeit.(*)

(*) Depth personality.

To be sure, we should not forget that this vegetative Tiefenpersonlichkeit is by no means a psychologically unambiguous conception. The events of the vasovegetative system must interfere in every cortical function, in every psychic happening. To be sure, the affectivities appear to be bound in some special manner to the interbrain, and every more primitive experience appears connected with a stronger resonance to the vasovegetative mechanisms. This is already suggested by the investigations of the so-called physical expression of the feelings, a term that might perhaps better be replaced by the " expression of the bodily manifestations of affections. For, in addition to the emotional phase, the conceptual imaginative intellectual phases to which the emotion is attached are always important, and we cannot understand the results obtained by Pavlov and Heyer, who show that the character of the object presented will determine the character of the secretion of gastric juices, if we limit our consideration to the emotions only. (Compare, in this connection, the statements made by Schilder in Schwartz's book.) We may indeed say that in general the vasovegetative phenomena become more extensive with a decreasing in the cortical function and with its becoming more primitive. Wherever the affective mechanisms come into the foreground the cortical function presents more primitive traits. Dislocations, condensations, defective differentiation of details ensue, and modes of thought familiar to us from the primitive state and from childhood put in their appearance. We may say, by way of abbreviation, that a fully developed cortical function is connected with clearly defined images which are productive of expedient action, and that this cortical function will regress to a primitive stage if the vasovegetative phase becomes more pronounced. We may, if we wish, take as our point of departure the experience, proved by psychoanalysis, that thought characterized by condensations, displacements, and symbolic formations corresponds to an ontogenetically and phylogenetically earlier stage of development. We must furthermore be perfectly clear as to the fact that affectivity, instinctive impulses, are the inalienable possession of all the living matter which, owing to its profound evolutionary roots, has its seat in the deeper sections of the brain. But after what we have already stated, it is clear that hypnosis applies itself to strata of primitive impulses. The attitude of the suggested person, in its goal-inhibited masochistic trend recognizing authority in a magic degree, is very evidently archaic and represents a primitive experience. It should not surprise us to learn that this attitude has particularly close relations with the phylogenetically deep-lying vasovegetative system. The effects of hypnosis are predominantly in the vasovegetative realm. We thus find that the results of psychological analysis have the closest possible relation with the results of physiological analysis. Both point to the fact that we must behold in hypnosis a primitive, archaic regressive phenomenon.

We therefore hold fully the view that the phenomena of hypnosis must be understood on the basis of the psychology and the psycho-physiology of the hypnotized. Alrutz thought it possible to show that an emanation proceeds from the hypnotizer which has a direct physical influence on the hypnotized. We have not observed any phenomena that would justify such a conclusion.