THE NERVOUS SYSTEM AND ORGANS OF SENSE 403 



, flcai^IL 



uninjured in any way, we find that tlie frog acts spontaneously. It tries to 

 escape when caught. It feels hungry and seeks food. It is capable of 

 voluntary action. It acts like a normal individual. 



Functions of the Cerebrum. — In general, the functions of the 



different parts of the brain in man agree with those functions 



we have ah'eady ob- 



ser\'e(l in the frog. The 



cerebrum has to do with 



conscious activity; that 



is, thought. It presides 



over what we call our 



thoughts, our will, and 



our sensations. Each 



part of the area of the 



outer layer of the cere- 

 brum is given over to 



some one of the differ- 

 ent functions of speech, 



hearing, sight, touch, 



movements of bodily 



parts. The movement 



of the smallest part of 



the body has its definite 



localized center in the 



cerebrum. Experiments have been performed on monkeys, and 



these, together with observations made on persons who had lost 



the power of move- 

 ment of certain parts 

 of the body, and 

 who, after death, 

 were found to have 

 had diseases localized 

 in certain parts of the 

 cerebrum, have given to us our 

 knowledge on this subject. 



Reflex Actions ; their Meaning. — 



TV- „ f ji, ii f ■ 1 If through disease ox for other 



Diagram of tho path of a. Mniijlo " '" fo 



nervous reflex aitiuu. rcasons the ccrebrum does not 



Regions of the head and action of the different 

 parts of the brain. 



