instance, the flavor was that of strong Roquefort cheese, and in another of pears.
The difference between illusions and hallucinations can be recognized without difficulty, for the latter are entirely cerebral in origin, and do not require, as do the former, a material basis. They can not be produced by any defects or derangements of the sensory organs, or by any external circumstances tending to interfere with the normal action of these organs. We have to consider them now as resulting from disorder of the perceptional ganglia without the implication of those parts of the brain which are concerned in the production of intellect, emotion, or will.
The case of Nicolai, the German bookseller, is a striking instance of hallucinations of sight. For ten months he had been a good deal disturbed by several melancholy incidents. A customary blood-letting was omitted, and added to all was an unusual press of business matters. One morning he suddenly perceived, at apparently the distance of ten steps, a form like that of a deceased person. The phantom continued only for about ten minutes, but in the afternoon it reappeared. He arose and went to another room, the apparition accompanying him—disappearing, however, at intervals, and always maintaining the erect posture. Later there appeared other figures, unlike the first.
After the first day the figure of the deceased person no longer appeared, but its place was supplied by many other phantoms, sometimes representing acquaintances, but mostly strangers. After about four weeks he began to hear them talk. The application of leeches to the arms relieved him promptly of his hallucinations.
Hallucinations of hearing are more common than those of any other of the special senses, and, according to my experience, are more apt to lead to further mental disorder. Far more people kill themselves under the influence of hallucinations of hearing than from those of all the other senses combined. The reiteration in the ears, during every minute of the day, of the command to jump into the river, to plunge a convenient knife into the heart, and so on, day in and day out, is calculated to shake the power of control of the strongest-minded.
Sometimes a single word or a few words constitute the hallucination, but in their more complex character they are sentences and even long discourses. No instance that has come under my observation equals that of a lady who hears recited to her long pieces of original poetry or prose. She has repeatedly written down these recitations and brought them to me. This lady had a strong hereditary tendency to insanity, and, shortly after the development of the hallucinations referred to, she imbibed the delusion that she had committed the "unpardonable sin." She made two attempts at suicide, and is still insane, but has—an unusual circumstance—lost the delu-