CHAP. XXV.] PHRENOLOGY : OLD AND NEW. 533 



power at will to call into existence conditions which 

 almost never exist in the case of disease in the human 

 subject that is, he can produce symmetrical destructions 

 in corresponding regions of the two Hemispheres, and 

 knowing that such lesions alone exist, can thereafter most 

 carefully test the animal's condition in respect of the 

 sense-endowment supposed to he interfered with. 



Taking first of all the case of the sense of Sight, we find 

 Ferrier localizing its ' perceptive centre ' in the ' angular 

 gyrus ' and part of the * supra -marginal lobule ' (fig. 174). 



FIG. 174. Brain of Monkey, showing shaded area corresponding with so-called 

 Visual Centre in the cortex of left Cerebral Hemisphere. (Ferrier.) 



Destruction of such parts on one side in an animal rendered 

 insensible by chloroform, seemed to produce blindness 

 of the opposite eye for a day or more judging from the 

 effects of bandaging the other eye for a time and then 

 removing the bandage, so as to be able to watch and 

 contrast the animal's behaviour under these different con- 

 ditions. After a day or two, the animal experimented 

 upon again appeared to see with both eyes. Where, 

 however, these regions of the cortex had been destroyed in 

 both Hemispheres, the creature became blind in both 



