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 lenticel, a characteristic preparation from the elder-tree. His eyes roved over his intent fellow-students, and Wedderburn suddenly glanced over his shoulder at him with a queer expression in his eyes. The mental excitement that had kept Hill at an abnormal pitch of vigour these two days gave way to a curious nervous tension. His book of answers was beside him. He did not write down what the thing was, but with one eye at the microscope he began making a hasty sketch of it.
