592 



PSYCHOLOGY. 



vation should establish itself after loss of brain-tissue, 

 and why incoming stimuli should find their way out again, 

 after an interval, by their former paths. I can now explain 

 this a little better. Let S' be the dog's hearing-centre when 

 he receives the command ' Give your paw.' This used to 

 discharge into the motor centre M', of whose discharge S"* 

 represents the kinsesthetic effect ; but now M' has been de- 

 stroyed by an operation, so that S' discharges as it can, into 

 other movements of the body, whimpering, raising the 

 wrong paw, etc. The kinsesthetic centre S' meanwhile has- 



ML. 



T3:\ 



Fig. 98. 



been awakened by the order S', and the poor animal's mind 

 tingles with expectation and desire of certain incoming sen- 

 sations which are entirely at variance with those which the 

 really executed movements give. None of the latter sensa- 

 tions arouse a ' motor circle,' for they are displeasing and 

 inhibitory. But w^hen, by random accident, S' and S' do 

 discharge into a path leading through M\ by which ih&paiois 

 again given, and S' is excited at last from without as well as 

 from within, there are no inhibitions and the ' motor circle ' 

 is formed : S' discharges into M"* over and over again, and 

 the path from the one spot to the other is so much deepened 

 that at last it becomes organized as the regular channel of 

 efflux when S' is aroused. No other path has a chance of 

 being organized in like degree. 



