THE PROPERTIES OF PROTOPLASM 9 



Just as you cannot at once get the great door 

 into movement so neither can you instantaneously 

 arrest its swing, it keeps on moving by its momentum 

 after the arresting force has begun to be applied. 

 Under certain conditions, therefore, activity and 

 not inactivity may be the expression of proto- 

 plasmic inertia : continued activity after, say, an 

 inhibitory stimulus has been applied and for the time 

 being disregarded post-stimulant activity, and also 

 when activity has been in progress and the causal 

 stimulus has been removed, the activity continues 

 post-stimulant both are cases of maintenance of 

 the status quo ante, that is, are inertial. Conversely, 

 under certain conditions, inhibition partial or 

 complete arrest of activity may be an expression 

 of affectability. Protoplasmic activity, which is 

 not the result of the impinging of stimuli, which is 

 not due to environmental influence and is exhibited 

 even under conditions tending to suppress it, is 

 inertial : under this head come certain factors in 

 spontaneity and automatism. Thus we may have- 

 Either activity \ 



or j- arising from affectability ; 



Inhibition of activity J 



and conversely, 



either non-response in disregard of stimulus, if 

 inactivity is the status quo ante, 



or 



inertia, 

 response in disregard of stimulus, if activity is 



the status quo ante. 



arising from 

 functional 



