Page:Principles of Psychology (1890) v1.djvu/71

Rh sight altogether. Recent pathological annals seem to offer a few such cases. Meanwhile there are a number of cases of mental blindness, especially for written language, coupled with hemianopsia, usually of the rightward field of view. These are all explicable by the breaking down, through disease, of the connecting tracts between the occipital lobes and other parts of the brain, especially those which go to the centres for speech in the frontal and temporal regions of the left hemisphere. They are to be classed among disturbances of conduction or of association; and nowhere can I find any fact which should force us to believe that optical images need be lost in mental blindness, or that the cerebral centres for such images are locally distinct from those for direct sensations from the eyes.

Where an object fails to be recognized by sight, it often happens that the patient will recognize and name it as soon as he touches it with his hand. This shows in an