THE NEKVOTJS SYSTEM. 471 



creased or diminished (inhibition) by afferent impulses. This is the 

 case in whatever way the centre has caused the action, whether of itself, 

 or by means of previous afferent impulses. The action, by which a 

 centre is capable of being inhibited or exalted, has been well shown in 

 the case of the vaso-motor centre, before described. This power, which 

 can be exerted from the periphery, is very important in regulating the 

 action even of partially automatic centres such as the respiratory centre. 



