A girl of about twenty-five, with a countenance only relieved from ugliness by a fine pair of bright dark eyes, was led in by an assistant and seated in a chair. She was of the usual type seen in the streets of Islington, poorly dressed with some attempt at faded finery--probably a workgirl in some city factory. She cast an uneasy glance upon the audience, and then turned towards the doctor, who drew his chair towards the patient so that her knees nearly touched his. It was a case of nervous "Hemianopsie," or one-eyed vision, he explained. Now the existence of this has always been denied, therefore the experiment was of the most intense interest to every medical man present. First the doctor, after ordering the patient to look him straight in the face, held a pencil on the left side of her head, and found that, in common with most of us, she was conscious of its presence without moving her eyes, even when it was almost at the level of her ear. Then he tried the same experiment on the right side of the face, when it was at once plain that the power of lateral vision had broken down--for she answered, "No, sir. No, no," as he moved the pencil to and fro with the inquiry whether she could see it. Nevertheless he demonstrated that the power of seeing straight was quite unimpaired, and presently he gave to his assistant a kind of glass hemisphere, which he placed over the girl's head, and by which he measured the exact point on its scale where the power of lateral vision ceased. This being found and noted, Professor Deboutin placed his hand upon the patient's eyes, and with a brief "You may sleep now, my girl," in broken English, she was asleep in a few seconds. Then came the lecture. He verbally dissected her, giving a full and lucid explanation of the nervous system, from the spinal marrow and its termination in the coccyx, up to the cortex of the brain, in which he was of opinion that there was in that case a lesion--probably curable--amply accounting for the phenomenon present. So clear, indeed, were his remarks that even a layman could follow them. At last the doctor awoke the patient, and was about to proceed with another experiment when his quick eye noticed a hardly-perceptible flutter of the eyelids. "Ah, you are tired," he said. "It is enough." And he conducted her to the little side door that gave exit from the platform.