Fluoresceinated IgG was injected centrally into the rabbit's cornea and both its rate of loss from the tissue and its rate of spread in the stroma were estimated by objective fluorometry. A new technique for determining the rate of loss was established which required only the measurement of the maximum fluorescence in the tissue. The rate at which freshly formed IgG in the blood would arrive at the central regions of the cornea was estimated for the human eye. As penetration continues from the limbus and the protein is lost to the aqueous humor, a standing concentration gradient is set up with a minimum at the corneal center. Calculation suggests that this gradient should be small for IgG in the human eye.