34 



PSYCHOLOGY. 



Eveu when tlie entire motor zone of a dog is removed, 

 there is no permanent paralysis of any part, but only this 

 curious sort of relative inertia when the two sides of the 

 body are compared ; and this itself becomes hardly notice- 

 able after a number of weeks have elapsed. Prof. Goltz 

 has described a dog whose entire left hemisphere was de- 

 stroyed, and who retained only a slight motor inertia on the 

 right half of the body. In particular he could use his right 



Fig. 6. — Left Hemisphere of Monkey's Brain. Outer Surface. 



paw for holding a bone whilst gnawing it, or for reaching 

 after a piece of meat. Had he been taught to give his paw 

 before the operations, it would have been curious to see 

 whether that faculty also came back. His tactile sensi- 

 bility was permanently diminished on the right side.* In 

 monkeys a genuine paralysis follows upon ablations of the 

 cortex in the motor region. This paralysis affects parts of 

 the body which vary with the brain-parts removed. The 

 monkey's opposite arm or leg hangs flaccid, or at most takes a 

 small part in associated movements. When the entire region 

 is removed there is a genuine and permanent hemiplegia 

 in which the arm is more affected than the leg ; and this is 



Goltz : Pfliiger's Archiv, XLii. 419. 



