THE NERVOUS SYSTEM 245 



53. The Functions of the Cranial Ganglia. The uses of the 

 smaller gray masses lying at the base of the brain are not 

 well ascertained ; and, on account of their position, so remote 

 from the surface, it would at first seem well-nigh impossible 

 to study them. But, from the results following diseases in 

 these parts, and from experiments upon inferior animals, they 

 are becoming gradually better understood ; and there is reason 

 to believe that eventually the physiological office of each part 

 will be clearly ascertained and defined. It is believed, how- 

 ever, but not absolutely proved, that the anterior masses, like 

 the anterior roots of the spinal nerves and the anterior col- 

 umns of the cord, are concerned in the production of motion ; 

 in fact, that they are the central organs of that function. The 

 posterior gray masses are, on the contrary, supposed to be the 

 seat of sensation. 



54. The Function of the Cerebellum. The function of the 

 cerebellum, or " little brain," is the direction of the movements 

 of the voluntary muscles. When this organ is the seat of 

 disease or injury, it is usually observed that the person is 

 unable to execute orderly and regular acts, but moves in a 

 confused manner as if in a state of intoxication. Like the 

 larger brain, or cerebrum, it appears to be devoid of feeling ; 

 but it takes no part in the operations of the mind. 



55. The Function of the Cerebrum. The cerebrum, or brain 

 proper, is the seat of the mind ;. or, speaking more exactly, it 

 is the material instrument by which the mind acts ; and, as it 

 occupies the highest position in the body, so it fulfils the lofti- 

 est uses. All the other organs are subordinate to it: the 

 senses are its messengers, which bring it information from the 

 outer world, and the organs of motion are its servants, which 

 execute its commands. Here, as in the nervous apparatus of 

 lower grade already considered, the gray matter is the element 

 of power; and in proportion as this substance increases in 

 extent, and in proportion to the number of convolutions in 

 the hemispheres, do the mental faculties expand. 



53. The uses of the smaller gray masses at the base of the brain ? 



54. Function of the cerebellum ? When it is diseased ? 



55. Where is the seat of the mind ? The subordination of the other organs ? The gray 

 matter? 



