All of the rats were enuculated one of the eyes, and then trained to perfect discrimination in the box manufactured following to M.F. Fritz's opinion. Nextly they were subjected to subcortical injury; -especially our experiments were directed toward the effect of thalamic lesions of the half, -before relearning the habit. The brains were then prepared for sektioning. A macroscopic estimation of the amount of injury was made and microscopic study, too. From these sections we have estimated the depth of injury in each animals and the degree of fiber tract degenerations. The subcortical injury which was given opposite to the healthy eye, abolishes all reactions to discrete visual object, but does not interfer with the formation of the reaction to the light versus darkness, and which was given same to the healthy eye does not, mostly, affect all reactions to them. These experiments does not decide to completely, but it may be conceivable that optic-nerves semicross at the optic-nerves acrossing part, and non-cross fibers are very few.