THE PURPOSE of this investigation is to determine the effect of cortisone on the formation of corneal vessels, the technique of formation and measurement of corneal vessels described by Campbell and Michaelson1 being used. In this method a standard lesion of the cornea is produced by the application for a constant time of a platinum-wire cautery supplied with a constant voltage. The area of vascularization produced by the standard lesion is demarcated by India ink injected after the death of the animal. METHOD The experiments were carried out with rabbits of various weights. Prior to cauterization, 2 drops of 1% tetracaine hydrochloride was instilled into the conjunctival sac. The lesion was placed in the 12-o'clock meridian with its center about 2.5 mm. from the limbus. Precision in this matter, however, was not possible because of the difficulty in determining clinically the exact position of the limbus. The lesion was