44 DR. HILL, PROM REFLEX ACTION TO VOLITION. 



to say at what level in the animal kingdom this advance 

 occurs, although it is easy to point out animals in which 

 memory is clearly present, and others like the jelly fish in 

 which such a function, if it exist, is hardly to be shown. In 

 the great majority of animals, although in varying degree, 

 the passage of the impulse is accompanied by molecular 

 changes, which result in its being stored. It is not merely 

 reflected as in a glass, but fixed as in a photograph. Infinite 

 possibilities are opened up by this capacity of the system for 

 storing impulses; possibilities of the combination and com- 

 parison of the impulse received from the outer world and 

 about to be discharged in movement, not only with other 

 impressions concurrently received, but also Avith all the 

 accumulated experiences of the past. Reverting to our 

 former illustration of the effects produced when one person 

 treads upon another person's toe, we see how the impulse 

 may not only flow over into the muscles which withdraw the 

 foot, or return it in a kick, but may be combined with im- 

 pressions received through the eye which awaken memories ot 

 former accidents of the same kind, and the troubles which 

 resulted from a hasty resentment, so that the movement made 

 is not the reflection of one impulse only, but of several ; nor 

 of current impulses only, but of these combined with others 

 long ago received. Now we begin to feel as if we had 

 reached the outskirts of thought. If we could watch the 

 machinery in motion, we should see not the shuttle flying back- 

 wards and forwards, weaving, twisting, intertwining threads, 

 but nerve currents starting in different, perhaps distant parts 

 of the central system, hastening, checking, combining, dis- 

 parting, to form the pattern which we recognize as a thought. 

 My survey of the subject must be confusingly hasty, but 

 there is one other feature of the network, a consideration of 

 which throws a brilliant light upon its mode of working. 

 Hitherto wehave spoken of reflex action only. This is the web 

 upon which is woven the many-coloured fabric of intelligence 

 and emotion. From what peculiarities in its quality and 

 amount do the less easily denned phenomena of mental 

 action acquire their colour? The cortex of the brain is, we 

 know, the seat of these higher processes. But twenty years 

 ago it was thought that although the elements of which the 

 cortex is composed are simple, although there are no local 

 peculiarities in their arrangement, although the cortex is in a 

 word remarkably uniform in constitution, its mode of action 

 must be complicated to a degree which baffled investigation. 



