FUNCTIONS OF GANGLION [C CELLS. 517 



nerve, going to the salivary gland, and the result is an in- 

 creased secretion of saliva. 



2. Coordination. There are but few reflex acts that do not 

 require the cooperation of several cells, and these work together 

 in an orderly manner, the resulting activity being well arranged 

 and usually adapted to some purpose. The first act of the re- 

 ceiving cells of this reflex centre must then be to distribute and 

 direct the impulse into those channels which lead to groups of 

 cells capable of sending impulses in an orderly and definite 

 direction. This directing and arranging power is spoken of as 

 coordination, and probably is an attribute common to all nerve 

 cells. 



3. Augmentation. Usually the force of the reflected efferent 

 impulse bears a direct relation to the afferent impulse as deter- 

 mined by the strength of the stimulus. Thus, if the amount of 

 pepper on the tongue be much increased, not only is the flow of 

 saliva greater, but the stimulus spreads from one central cell to 

 another until the neighboring centres are affected. Thus we often 

 find the lachrymal glands are also influenced by very strong 

 stimulation of the tongue, and pour out their secretion, as is said, 

 " in sympathy " with the mouth glands. But the amount of the 

 afferent impulse is not the only factor in determining the amount 

 of response to be reflected along the efferent channels. Some 

 nerve cells have a distinct power of increasing the amount of re- 

 sponse to be given to a given stimulus. When an irritant falls 

 near the laryngeal opening, a very different effect is produced, 

 and the vastly greater response to an equal stimulus depends 

 rather on the augmenting power of some central cells than upon 

 any greater sensibility of the local mechanisms. 



4. Inhibition. Under certain circumstances, such as pre-occu- 

 pation, etc., which will be more fully explained presently, nerve 

 cells withhold the transmission of a stimulus, or lessen the im- 

 pulse reflected so as to produce little or no effect ; this is called 

 inhibition. 



5. Automatism. Nerve cells are supposed to have the power 

 of originating impulses; e.g., those carrying on operations which 

 require to be of a more or less permanent kind, such as the closure 





