OF THE PHYSIOLOGICAL INSTITUTE OF BRESLAU.
THE people of the city of Breslau were, several months ago, greatly-excited over the performances of a professor of animal magnetism who seemed to exercise extraordinary power. His subjects were taken indiscriminately from his audiences, and all, even physicians and men of science, who allowed themselves to be experimented upon, yielded to his control and contributed to his triumph. Dr. R. Heidenhain, Professor of Physiology and Director of the Physiological Institute of Breslau, on the invitation of the friends of science, delivered a lecture on the subject, in which he undertook to give a physiological explanation of the strange effects obtained by the magnetizer, and showed by experiment that the same results could be obtained by the sight or presence of inanimate objects. The following is an abridged translation of this address.—[Ed.
One of the essential symptoms of the hypnotic sleep is the more or less complete loss of consciousness. It is only in a complete state of hypnotism that persons subjected to the experiment preserve a remembrance of what has passed during their sleep. In some cases the memory is only suspended, and on awaking we may be able to revive the recollection by evoking an association of ideas which will put the subject in train. Sensorial perceptions take place even in the most complete hypnotism, but the power of transforming them into conscious representations, and consequently of fixing them in the memory, is absent. Have we not often had experience in the waking state of external perceptions which did not pass the threshold of consciousness because our attention was absorbed or distracted at the time? Have we not heard words pronounced around us to which we attached no meaning, which were nevertheless perceived by us, if we may speak in that manner, without our knowledge, since we may call them to mind by an effort of memory, provided they have not yet been effaced by a more recent impression?
The immediate affection of the senses and conscious perception are distinct physiological conditions, the latter of which supposes a holding of the attention. As the hypnotic's faculty of perceiving a sensation declines, his power of being conscious of it diminishes in a corresponding degree. Then, sensorial impressions which do not excite consciousness give way to movements which are accomplished almost without our control. A person walking in the street, absorbed in his thoughts, receives the visual impression of the passers-by on his retina without paying attention to them, and unconsciously performs the movements