RECENT psychology has an abundant literature. Wundt, James, and its other distinguished exponents should he gratified by the activity of their many disciples. The book before us is one of the best outcomes of this activity. It differs from many books on the same and similar subjects in its method of discussion. It is also original in some of the points of view taken by the author.

        This book commends itself not only to psychologists, but also to physicians, and especially to alienists and neurologists, for whom it contains many suggestions, both as to the nature of some diseases of the nervous system and also as to their diagnosis, prognosis, and treatment. In this connection, one of its most practical aspects comes ont in the discussion of the types of amnesia. The author shows, for instance, that amnesia may be normal and merely temporary and functional; or it may be irretraceable and curable; or it may be absolute and incurable, and more than this, he believes that he can demonstrate that it is possible, by making use of the methods of the psychologist, to differentiate these forms of amnesia, to refer them to their anatomical and physiological bases, to separate the curable from the incurable, and to treat the latter by special methods which arise out of investigations into the psychical nature of the subjects of the amnesia. The cases which he adduces to illustrate this position are of great interest, and in most respects convincing.

        Another of the practical aspects of the work is where the author considers the relations of the, subconscious to insanity, showing, as he believes, how in hypnotic and post-hypnotic conditions we hold the keys to the forms of conceptional and impulsive insanity. The nature or mechanism of imperative concepts, insistent ideas, and uncontrollable impulses is best understood by a study of conditions of normal and abnormal suggestibility and comparative studies of the conscious and subconscious self. It is held that those forms of insanity which are exhibited by insistent ideas, imperative concepts, irresistible impulses, and changes of personality have at their basis a disaggregation of consciousness, a dissociation of the primary and secondary subconscious selves. While we are not prepared to fully admit this thesis, the view is a highly suggestive one, and points the way to the proper study of the abnormal mental phenomena of these disorders. The methods adopted by Sidis for testing the subconscious memories, and of treating cases of amnesia, are worthy of the practical physician's attention. He also refers to methods used by him to run together into one the alternating personalities which are exhibited by some of the most extraordinary of the amnesic cases.

        We have referred to some of the practical aspects of this book first because we are addressing ourselves to medical readers. The entire work is, however, worthy of careful and close reading. Occasionally diffuse and repetitive, the author is, as a rule, direct and lucid. In some places he shows an unusual facility in making clear some of the abstruse terms and propositions of modern psychology. Nowhere have we seen a clearer presentation of the true meaning of suggestion and suggestibility. He defines suggestion as the intrusion into the mind of an idea; met with more or less opposition by the person; accepted uncritically at last; and realized un reflectively, almost automatically.

        The book has a brief but interesting introduction from the pen of Prof. William James, in whose laboratory at the Harvard University much of the work embodied in the book was done.

        Sidis has an interesting but just comparison of the merits of the German and French schools of psychology. As he states, the French care more for clinical cases than for the minute laboratory experiments which are so dear to the heart of the German. The German concept of the subconscious has been vague, and has rather the character of a mechanical than of a psychical process. The German results have been aptly characterized by James as the "elaboration of the obvious." The English and Americans, as well as the French, have worked along the lines of the subconscious with more insight if not in some directions with the same thoroughness as the Germans.

        In Chapter III., Sidis discusses the subject of especial interest to the physician engaged in neurological practice—the treatment of nervous diseases in general, mental diseases, and those affections which are often referred to as on the borderland between sanity and insanity. He starts out with the dictum" that every man in his full, normal, waking state is more or less suggestible."

        Normal suggestibility is directly the opposite of abnormal suggestibility; in the latter it varies as direct suggestion and inversely as indirect suggestion—that is, in abnormal subjects, as those suffering from grave hysteria or under hypnosis, the more direct the suggestion the more probable it is that it will be carried out; while in the former it is inversely as direct, and directly as indirect suggestion. The normal man does not do what is suggested to him directly, either because he has too much sense or because he is too obstinate to follow the suggestion. The conditions of abnormal suggestibility, which are the same as those of hypnosis, are (1) fixation of attention; (2) monotony; (3) limitation of voluntary movements; (4) limitation of the field of consciousness; and (5) inhibition.

        Sidis devotes a large part of one chapter to combating the sufficiency of Carpenter's doctrine of unconscious cerebration to account for the phenomena of hypnotic memory. His arguments on this score, while interesting, are scarcely of a convincing sort, and seem in some parts like a substitution of assertions for a more tangible hypothesis. To say that the phenomena are not a result of unconscious cerebration, but simply evidences of the existence of another self, is not an explanation of the phenomena.

        Some of the interesting records of double and triple personality, both as exemplified in hypnotic subjects and in the records of unusual cases of periodic amnesia, are reproduced, and the subject of automatic writing and its bearing on the problems under discussion is considered.

       He holds that much evidence can be adduced to show the presence of a sub waking self in a normal individual; that the state of cleavage of personality and consciousness takes place not only in those who are hypnotic, but is more or less demonstrable in all normal individuals.

       Part III., which applies the facts and theories of suggestibility to the study of society, will be found of interest to the general reader as well as to the student of psychology and psychiatry.

       We can cordially commend this book to all who wish to keep pace with the most valuable of recent additions to psychological literature.

C. K. M.