Page:Popular Science Monthly Volume 46.djvu/743

Rh disease he did not recognize his surroundings. On going out for the first time the streets of the city no longer seemed familiar; on coming back he did not know his own house. After a few weeks, however, all his memories had returned excepting those of the letters and figures named; but as the loss of these put a stop to his reading and to all his business life, the small defect of memory was for him a serious thing. Experience has shown that such a defect is due to a small area of disease in one part of the brain. Such cases are not uncommon, and illustrate the separateness of our various memories and their dependence upon a sound brain.

Among the curiosities of thought which the physician meets with, unexpected perceptions suddenly appearing before the mind with the same vividness as ordinary perceptions, but without any accompanying external excitant, are not uncommon. A person may look at an empty chair and yet see a familiar form seated in that chair, and may even hear remarks made by this imaginary figure and not doubt for a moment that the figure is an actual entity.

I have seen persons talking with such imaginary individuals, and have had them assure me that they were as sure of their presence and of their voices as they were of my own. I have seen persons manifest the greatest alarm at the presence of animals about them, and refuse to believe from assurance that those animals were not there.

A young woman, having once been frightened by the sudden presentation to her of a white mouse, has been troubled for years by seeing this mouse running about her, upon her clothing, upon anything she is handling, and even upon her food; and, as a result, she is in a state of constant agitation and perplexity, though at times convinced that this is the product of her mind. She washes her hands and her clothing frequently because she is convinced that this animal has made them dirty; and she can not divest herself of the belief that it is real.

I have sometimes been able to convince persons that such fancied figures were not real by asking them to push one eyeball up a little with the finger. This makes all objects about them seem double, as any one can prove to himself, but it does not double the false image—the product of the mind. The young woman just mentioned was much comforted by this device.

Argument alone does not suffice in such a condition to convince one that an impression is erroneous. Thus, a woman who had gradually become totally blind, and was willing to admit that she could see nothing whatever, could not be convinced that she was not surrounded constantly by multitudes of little gnomelike pygmies, whom, she persistently declared, she saw before her, and whom she was afraid that she would step upon or crush by any