THE STUDY OF THE NERVOUS SYSTEM. 9 



logical study to determine the character and mode of action of 

 nerve protoplasm. 



Numerous operative experiments have been directed toward 

 the study of the function of various parts of the brain and of other 

 nervous organs by stimulation, extirpation, poisoning, etc. Ex- 

 amples of such work are found in the numerous researches on 

 the function of the cerebellum and upon the localization of func- 

 tion in the cerebral cortex. Other studies take account of the 

 modifications of normal action following upon the destruction 

 of any conduction path or center anatomically known. Still others 

 regard the modifications of responses to stimuli after the appli- 

 cation of selective poisons such as curare and nicotin, which affect 

 respectively the motor end plates and certain elements of the 

 sympathetic system. 



The functions of sense organs have been studied by experiments 

 to determine the conditions of their functioning, the character 

 of stimuH proper to each kind of sense organ, the range of stimu- 

 lation, etc. Examples are seen in recently renewed studies upon 

 the ear and lateral line organs and upon the gustatory organs 

 of fishes. 



The methods by observation may or may not be experimental 

 in the sense that natural conditions are controlled or simplified 

 by the observer without physical interference with the organism 

 or its nervous mechanisms. This form of study is especially 

 developed in the field of animal behavior and physiological 

 psychology. 



The main object in the study of the nervous system is to dis- 

 cover what functional relationships are provided for by each of its 

 parts. The words "functional relationships" imply actions and 

 organs which act. The nervous system is in relation both structur- 

 ally and functionally with all parts of the organism. All activities 

 are directly or indirectly dependent upon the proper functioning 

 of the nervous system. The study of the nervous system implies 

 a knowledge of the whole structure and the whole life of the organ- 

 ism. This breadth of view and attention to the functional side 

 are two factors essential to the right attitude in the study of the 

 nervous system which have been scarcely well enough appreciated. 



