434 MAN BECOMES THE CONQUEROR OF THE WORLD 



auditory' 

 araoc ^ 



motor areec 



s&nsory area 



thinking*, 

 abstract, 

 concentrati 



thinking" 

 learning^ and, 

 understSmdiiTg- 



— Cerebrum 

 visual area 



.Cerebellum 



- medulla 

 ^coordination 



According to the observations of physicians and the experi- 

 mentations of scientists certain functions are thought to be 

 controlled by different portions of the brain. 



Localization of functions. In a general way, our central 

 nervous system is like that of the frog. The autonomic activi- 

 ties are largely con- 

 trolled outside the 

 brain. The cerebel- 

 lum and spinal cord 

 take care of the ha- 

 bitual reflexes which 

 we learned when 

 growing into child- 

 hood. The cerebrum 

 has to do with a large 

 number of conscious 

 activities. 



A large part of the 

 area of the outer 

 layer of the cerebrum 

 seems to be given over to some one of the different functions of 

 hearing, sight, touch, and movements of body parts. The move- 

 ment of the smallest part of the body appears to have its definite 

 localized center in the cerebrum. In addition, certain areas have 

 to do with association and memory; that is, the cells store 

 memories of past acts or things. Those areas have to do with 

 our voluntary actions, for the stored memories are really stored 

 sensory impressions. Voluntary acts, then, are the completion of 

 reflexes. Even reasoning may be explained as the association of 

 concepts, the relation of which is not close. Reasoning is per- 

 ceiving relationships in seemingly unrelated facts. 



Functions of the nervous system of man. There are several 

 types of activities over which the nervous system has control. 

 The first are the so-called autonomic activities of the body. The 

 heart beats and we breathe when we are asleep as well as when 

 we are awake. Our glands emit secretions and our kidney cells 

 excrete wastes, all without any consciousness on our part. 



A second kind of function is the kind of activity which once 

 was learned but now has become " second nature " or habitual. 

 If we have well-regulated body machines, we get up in the morning, 



