1) If an entire eye is removed from an embryo ofRana palustris, the tissues of the head are incapable of regenerating a new one. 2) There is no development of an eye if all of the eye-forming region of the fore-brain is destroyed before the medullary folds have closed. 3) Destroying any part of the fore-brain except the eye-forming region does not interfer with the normal development of the eye. 4) The eye-forming tissue of the fore-brain appears to have the power of self-differentiation as it will develop into a more or less normal optic cup when removed from its connection with the rest of the brain and without the presence of a lens. 5) Any ectoderm of the head appears to have the power to produce a lens provided it receives the proper stimulus. 6) Contact between the optic cup and the ectoderm is not necessarily the stimulus that leads to the development of a lens, as a lens can be formed from the ectoderm when the optic cup is some distance beneath the surface of the body. 7) A lens-like structure may be formed from the ectoderm when there is no optic cup on the same side of the head. The process appears to be a self - differentiation of lens-forming tissue of the ectoderm. 8) It seems probably that, under certain conditions, a lens can develop from the upper edge of the optic cup as is the case in the regeneration of the lens in the eye ofTriton.