HALLUCINATIONS.--The received definition of an hallucination is a false perception without any material basis, being formed entirely in the mind. An individual who sees pictures on a blank wall, or who hears voices when no sound reaches his ear, is hallucinated. “The reason for this being that the erroneous perception constituting the hallucination is found in that part of the brain which ordinarily requires the excitation of sensorial impressions for its functions.” In this view, hallucination is evidence of mental derangement and incipient insanity. This explanation is by no means sufficient for this class of facts. That a certain tract of brain can of itself give the mind complicated representations, never before seen or imaged in the mind, is not established. The reappearance of objects that have been seen is better explained, and still more satisfactorily, by causes which unite them all together, and with all like phenomena. George Combe says of a painter who inherited much of the patronage of Sir Joshua Reynolds, and believed himself to possess a talent superior to his, was so fully engaged that he had painted three hundred large and small portraits in one year. The fact appeared physically impossible, but the secret of his rapidity and astonishing success was this: He required but one sitting of his model. His method was as follows, as given by himself: “When a sitter came, I looked attentively on him for half an hour, sketching from time to time on the canvas. I did not require a longer sitting. I removed the canvas, and passed to another person. When I wished to continue the first portrait, I recalled the man to my mind. I placed him on the chair, where I perceived him as distinctly as though really there, and, I may add, in form and color more decidedly brilliant. I looked from time to time at the imaginary figure and went on painting, occasionally stopping to examine the picture exactly as though the original was before me; whenever I looked towards the chair I saw the man. This method made me very popular, and as I always caught the resemblance, the sitters were delighted that I spared them the annoying sittings of other painters.” This painter was far from incipient insanity. He was sensitive to impressions, and able by that organization to recall the image of the sitter, but not that of one who had not occupied the chair.