656 



PHYSIOLOGY OF THE CEREBRUM 



be removed from a dog, and then after the hemiamblyopia has disappeared the 

 motor zone also be removed, no additional effects on vision are produced. But 

 the remarkable thing is that the same is true if the operations be performed in 



commodation. 

 pil. 

 Convergence. 



Corp.Quocl. 



O.C 



Fio. 295. Schematic representation of the optic tracts, modified from Fuchs. 



Division of the optic tract at gg, or ce, or removal of the left occipital lobe produces right hemi- 

 anopia. In the first case there would be no reaction of the pupil to light on illuminating the 

 left half of either retina. Division of the chiasm at ss produces temporal hemianopia. 

 Division of the fibers at m abolishes the reaction of the pupil to light. The fibers connecting 

 the optical cortex (O.C.) with the midbrain (cf. page 657) and with other portions of the 

 cortex (Assoc.) (page 660) are shown. O.R., optical radiation; O.c., oculo motor nerve. 



reverse order. After the hemiamblyopia resulting from removal of the motor 

 zone has passed off, an extirpation within the occipital lobe is entirely without 

 effect. We shall discuss the significance of these facts further along (page 660). 



