It was just the kind of thing that the botanical professor was always doing. Like the income tax, it offered a premium to the cheat. It was a preparation under the microscope, a little glass slip held in its place on the stage of the instrument by light steel clips, and the inscription set forth that the slip was not to be moved. Each student was to go in turn to it, sketch it, write in his book of answers what he considered it to be, and return to his place. Now to move such a slip is a thing one can do by a chance movement of the finger, and in a fraction of a second. The professor's reason for decreeing that the slip should not be moved depended on the fact that the object he wanted identified was characteristic of a certain tree stem. In the position in which it was placed it was a difficult thing to recognise, but once the slip was moved so as to bring other parts of the preparation into view, its nature was obvious enough.
Hill came to this, flushed from a contest with staining re-agents, sat down on the little stool before the microscope, turned the mirror to get the best light, and then, out of sheer habit, shifted the slip. At once he remembered the prohibition, and, with an almost continuous motion of his hands, moved it back, and sat paralysed with astonishment at his action.
Then, slowly, he turned his head. The professor was out of the room; the demonstrator sat aloft on his impromptu rostrum, reading the Q. Jour. Mi. Sci.; the rest of the examinees were busy, and with their backs to him. Should he own up to the accident now? He knew quite clearly what the thing was. It was a
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