I propose to devote the time at my disposal cHefly to 

 a rapid sketch, of the functions of the nervous system, in 

 so far as they may throw some light on the problems of 

 mind ; though I shall also of necessity make frequent 

 use of some of the facts of psychology. A^Tiat I shall endea- 

 vour to show is that we have good ground for inferring 

 that mental operations are invariably accompanied by 

 phvsical changes ; that these changes occur in an unbroken 

 order ; and that side by side with their increasing com- 

 plexity and development we find an increasing complexity 

 and development of mental phenomena. I shall conclude 

 by a discussion as to what may be inferred as to matter 

 and what may legimately be included in the term mind. 



You have probably all seen such simple forms of life- 

 stuff as the amoebfe. An amoeba is a speck of that semi- 

 fluid, jelly-like substance which is the phj-sical basis of all 

 life, and by the changes of which aU the organisation and 

 functions of living beings become possible. The simpler 

 forms of this protoplasm are unstable, responding to 

 stimulus. They become lively in their movements on the 

 application of heat. They either seek or avoid the light. 

 Different parts become protruded and retracted; small 

 objects are included in the moving body, are passed 

 through it, and if nutrient are digested ; but there is no 

 visible differentiation of parts, there are no organs. 

 The entire functions of life — digestion, reproduction, loco- 

 motion, and, extraordinary as it may seem, response to such 

 stimuli as touch, light, and heat— are performed, not by 

 any one part of the organism, but by its life-stuff as a 

 whole. Ho that a quasi-nervous response to stimulus is 

 inherent in the simplest form of living matter. 



Higher up in the animal series we find that the proto- 

 plasm of the organism where it is most subject to irritat- 

 ing influences undergoes a structural change which trans- 

 mutes it into muscular tissue. Still higher up in the scale 

 of progressive organisation we find that external shocks or 

 stimuli are liable to happen more at one part of the 

 organism than at another; and that these shocks get to be 

 transmitted in definite directions. They make paths, as 

 it were, for themselves, and as the stimuli are frequently 

 repeated we get certain directions of the organic proto- 

 plasm so constantly traversed by these impulses that they 

 become, so to speak, well-beaten roads ; in other words, 

 the protoplasm is reconstructed by successive shocks into 



