THE SENSORY CENTERS OF THE BRAIN 



Visual Field 



881 



Occipital Lobes 



Fig. 216. Afferent paths connecting the retina with the visual area of the cerebral cortex. 



will cause blindness in one eye alone. Lesions, such as those produced 

 by the pressure of a pituitary tumor upon the chiasm, may destroy the 

 function of those fibers which are crossing in the chiasm, and as a re- 

 sult a type of blindness known as bitemporal hemianopsia results. This 

 is a loss of sight in the temporal half of both visual fields, occasioned 

 by destruction of the decussating fibers, which, as we have pointed 



