The one is a case, it may be, of slow atrophy of the optic nerve, proceeding from central disease of the brain--from pressure on the optic tracts of nerve within the skull, or from defective nutrition following losses of blood. We find the nerve glistening white and slightly cupped, the arteries small, the fundus otherwise healthy. In the other we recognize at once, in the fulness of the veins, their pulsation, and the marked excavation of the optic disc, the indications of excessive tension of the eyeball and undue pressure of the nerve. The first requires careful constitutional treatment and a long course of studied hygiene and medication; the second calls for direct and immediate interference, with the view of relieving the intra-ocular pressure. In the diagnosis of this great class of glaucomatous disease of the eye--disease {126} characterized of loss of vision, sometimes slow and sometimes rapid, but always characterized by definite ophthalmoscopic signs: cupping of the disc, pulsation, fullness of the veins, and it may be more or less haziness of the transparent media--ophthalmoscopy has rendered a most brilliant and inestimable service. Prior to the introduction of the use of this instrument the disease was of an unknown pathology; its results were fatal to vision, but there were no means of diagnosing the conditions attending the earlier stages, and blindness followed almost certainly and inevitably. The investigation of the disease has brought us a remedy in the excision of a portion of the iris--a practice introduced by Von Gräfe, of Berlin, and of which the success is in suitable cases most gratifying.