EXPERIMENTATION AND PHYSIOLOGY 



to maintain its balance upon the most difficult 

 places. If food is placed in its mouth it has 

 the power to swallow and digest it. Its incen- 

 tives only for initiative action are gone. If, on 

 the other hand, the cerebellum is removed and 

 the cerebrum is left, the animal has sense appre- 

 ciation but fails in muscular coordination. 

 Marshall Hall discovered that if a nerve pass- 

 ing to the spinal cord is stimulated, an im- 

 pulse is reflected back through a motor nerve 

 independent of the brain, and motion occurs 

 even though the brain be absent or the spinal 

 cord be divided. 



Then it was discovered that the voluntary 

 impulses to move certain muscles emanate from 

 certain parts of the brain. Fitsch and Hitzig, 

 in 1870, mapped out these areas in the dog's 

 brain, by using electric stimulation. Landois 

 and Eulenberg found that mechanical stimula- 

 tion or irritation has no effect on the centers, 

 but chemical stimulation, such as salt solution, 

 has. Following this Jackson discovered that 

 localized inflammation causes stimulation; and 

 the local relation of epilepsy to these motor 

 centers was established. The most careful 

 and valuable work was done by Ferrier upon 

 cerebral localization in monkeys. The brain 



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