Sunlight, as well as the light from the oxyhydrogen and electric-arc lamps, is white, and therefore shows us the parts in their natural coloring, which is claimed as a great advantage over all other sources of light. It is true that the yellow rays which are predominant in all other artificial lights make the mucous membrane appear redder than it really is, and the observer may be led to believe that a congestion exists if the patient be examined by white light first, and then by yellow light on different occasions. But as all our knowledge and appreciation of shades of color depend upon a comparison with a standard, it makes no difference whether this standard, as in the case before us, is a little redder when viewed by yellow light or not so red when seen by white light. This advantage of the white light is, therefore, not of much practical value, and the expense and difficulties connected with the use of the oxyhydrogen or electric arc-light for laryngoscopy fully outweigh any advantage which can be claimed for it. THE ART OF LARYNGOSCOPY.--Before entering upon a description of the details of the art it will be necessary to clearly understand the optical principle upon which the use of the laryngoscope is based, and, further, to remember that the object to be viewed is situated below the straight path of light and vision. The optical law referred to is, that "The angle of incidence is equal to the angle of reflection," and consequently, in order to illuminate the cavity of the larynx and to see its details, the laryngeal mirror must be placed in such a position in the fauces that the light is reflected downward. The light rays forming the laryngeal image will then be reflected from the surface of the laryngeal mirror into the eye of the observer. It should always be borne in mind that the image seen in the mirror is a reflected one, like the image of one's self seen in a looking-glass, so that what appears to be right is left, and vice versâ. On account of the difference in height of the parts forming the image, and because the mirror must be placed above and slightly behind the opening of the larynx, the picture appears reversed in an antero-posterior direction. The same holds good when viewing a drawing of a laryngeal image.