Another direction in which the century has seen enormous progress is in the introduction of instruments of precision. When I was a student in the early 60’s, instruction in microscopy was conspicuous only by its absence from our medical curriculum. Now every student who graduates is more or less of an accomplished microscopist, and carries into his practice the methods and observations which the microscope furnishes. At the same period I remember being greatly interested in a discussion which two of my teachers had as to whether it was possible to make an application accurately to the vocal chords in the larynx. Now every tyro in medicine makes such applications to the larynx as a routine procedure in cases requiring it, and similar methods have been applied by the ophthalmoscope to examine the interior of the eye; the rhinoscope, to examine the interior of the nose; the otoscope, for examination of the ear; and other similar instruments for examining all the other hollow organs in the body. If I add to these the hypodermatic syringe; the aspirator, which may be described as a large hypodermatic syringe for suction instead of injection; the clinical thermometer, which was introduced in the late 60’s; the hemostatic forceps, for controlling hemorrhage by seizing the blood-vessels and clamping them till we have time to tie them; and other instruments intended to facilitate our operative methods, it will be seen at once that the armamentarium of the modern surgeon is very different from that of his predecessor at the beginning, or even at the middle, of the century. THE RÖNTGEN RAY