distinguish green; but whether or not there are individuals who can recognise the three primitive colours accurately, and are yet unable to distinguish the secondary colours, must be left, Dr Hays remarked, to further observation to determine.

It also remains to be ascertained, whether any person having an imperfect perception of yellow, can recognise blue; or with an imperfect perception of yellow and blue, or of the lat ter alone, can distinguish red.

III. Memoir of the Case of a Gentleman born Blind, and successfully operated upon in the eighteenth year of his age; with Physiological Observations and Experiments. By J. C. AUGUST FRANZ, M.D., M.R.C.S. (Communicated to the Royal Society by Sir BENJAMIN C. BRODIE, Bart. F.R.S.)

The young gentleman who is the subject of this memoir had been affected from birth with strabismus of both eyes: the right eye was amaurotic, and the left deprived of sight by the opacity both of the crystalline lens and of its capsule. At the age of seventeen, an operation for the removal of the cataract of the left eye was performed by the author with complete success. On opening the eye for the first time, on the third day after the operation, the patient described his visual perception as being that of an extensive field of light, in which every thing appeared dull, confused, and in motion, and in which no object was distinguishable. On repeating the experiment two days afterwards, he described what he saw as a number of opaque watery spheres, which moved with the movements of the eye, but when the eye was at rest remained stationary, and their margins partially covered one another. Two days after this the same phenomena were observed, but the spheres were less opaque and somewhat transparent; their movements were more steady, and they appeared to cover each other more than before. He was now for the first time capable, as he said, of looking through these spheres, and of perceiving a difference, but merely a difference, in the surrounding objects. The appearance of spheres diminished daily; they became smaller, clearer, and more pellucid, allowed objects to be seen more distinctly, and disappeared entirely after two weeks. As soon as the sensibility of the retina had so far diminished as to allow the patient to view objects deliberately without pain, ribands differently coloured were presented to his eye. These different colours he could recognise, with the