behind and on the same side as the eye to be examined, at the level of the eye and the perforated mirror and the eye of the observer are kept from 10 to 20 inches in front of the eye and also at the same level. For the horse or ox under favorable conditions in a stall, the light of day coming from a fansash over the door may serve the purpose. Nicholas assures us that it may be accomplished even under the shadow of a shed or a tree. In such a case it is better not to have too much glare of light as the reflection from cornea and lens may prevent accurate observation. A somewhat cloudy day may therefore prove advantageous. In focusing the reflected light on the cornea, and then on the pupil and lens, any opacities in these will be shown as a grayish nebular reflection or a denser white according to their degree of opacity. The opacities in the cornea or aqueous, in front of the axis of vision in the lens move in the same direction and to the same degree as the eye rolls, while opacities on the posterior capsule or in the vitreous, move in a direction opposite to the motions of the eye, and to a degree corresponding to their distance back of the lens. Thus if the eye looks downward such opacities move upward; if it looks upward they move downward; if it looks inward they move outward; and if it looks outward they move inward. To secure an image of the fundus of the eye, including the entrance of the optic nerve (optic papilla), the tapetum, the pigmentary surface and retina and vessels, accommodation must be made for the normal refraction of the eye of the patient, and even for that of the observer. In the =emmetropic= (normal) eye, the rays leave the surface of the cornea parallel to each other and it may be possible for the observer to secure a good image on his retina, without the aid of lenses. In the =myopic= (short sighted) eye they assume a convergent course on leaving the cornea, and to secure a satisfactory image a biconcave or plano-concave lens must be interposed between the cornea of the patient and the eye of the observer. In the =hypermetropic= (long sighted) eye, the rays diverge in leaving the cornea of the patient, and a convex lens must be interposed between this and the eye of the observer, in order that the rays may be focused on the eye of the observer. To adapt the vision to the different eyes the modern ophthalmoscope is furnished with a series of lenses concave and convex, any one of which can be moved behind the hole in the mirror to suit the demands of the particular case. To make a satisfactory examination the pupil should be dilated as for oblique focal illumination. A 1:200 solution of apomorphia may be instilled into the eye (a drop or two) and in 20 to 25 minutes a satisfactory dilatation will have been secured. The effect of the homatropin will usually have disappeared in twenty-four hours. Determination of Static Refraction.