FERRIER'S EXPERIMENTS ON THE BRAIN. 87 



Figs. 4 and 5 represent the lateral and upper 

 surfaces of the brain of the monkey; the circles 

 and included numerals indicate certain areas on 

 the convolutions of the brain. Figs. 6 and 7 repre- 

 sent similar views of the human brain, and the 

 circles with their numerals indicate areas corre- 

 sponding approximately with the areas on the 

 monkey's brain similarly indicated. In his ex- 

 periments Ferrier examined each area in two ways. 

 The portion of brain experimented upon was excited 



Fig. 5. The Left Hemisphere of the Monkey. The circles and numerals have the 

 same significance as in last figure. 



by an electrical stimulus, and the muscular move- 

 ment in the body which resulted was carefully ob- 

 served and recorded ; as a converse experiment, the 

 same brain area was then destroyed, and the set 

 of movements in the body which were previously 

 stimulated were now found to be paralyzed. This 

 demonstrated that stimulation of a certain brain 

 area produced a certain set of movements in the 

 bod}-, and that when the same brain area was 

 destroyed, that set of movements was paralyzed. 



