THE BRAIN. 245 



keys." In the case of man we infer that there is a similar 

 location, and many cases of accident and disease have 

 helped in locating the functions. But these areas are not 

 sharply defined.. 



Left Hemisphere Better Developed. The "speech 

 center" is in the left hemisphere; the right eye and ear, 

 which connect with the left brain, are better developed 

 than the left, and in general the left hemisphere seems 

 superior (in right-handed persons) to the right. 



Location of Centers of Sensation. It is not so easy 

 to locate the centers of sensation as those for motion. For 

 we can see the resulting motion, but a sensation can only 

 be felt by the individual in whom it occurs. Still, some of 

 the sensation centers have been located, and it is likely 

 that in time we shall know much more on this subject. 

 The accompanying diagram shows some of these centers. 



The Functions of the Cerebellum. The cerebellum 

 is the center for regulating the actions of the skeletal mus- 

 cles. When we walk or run, or even stand still, a number 

 of muscles must act, and act in concert. The nerve im- 

 pulses originate in the cerebrum, but the cerebellum is the 

 center for harmonizing the action of these various muscles, 

 or coordinating them. When the cerebellum has been re- 

 moved from a pigeon the bird flutters, and, while possess- 

 ing the power to move, does not seem capable of any 

 regular and orderly movement. There is no loss of intelli- 

 gence, no paralysis. Of course, in this experiment there 

 is great disturbance of the system, and perhaps too much 

 is inferred from it. 



Functions of the Spinal Bulb. The spinal bulb is the 

 connection between the spinal cord and the brain. The 



