﻿MAR. 
  19, 
  1022 
  troland: 
  psychophysics 
  the 
  key 
  of 
  physics, 
  etc. 
  149 
  

  

  factors 
  in 
  the 
  external 
  environment 
  of 
  the 
  organism, 
  but 
  the 
  psycho- 
  

   physiologist 
  soon 
  finds 
  that 
  the 
  association 
  is 
  brought 
  about 
  purely 
  

   through 
  the 
  medium 
  of 
  factors 
  lying 
  within 
  the 
  organism. 
  He 
  finds 
  

   that 
  electro-magnetic 
  wave-lengths 
  entail 
  the 
  existence 
  of 
  color 
  only 
  

   if 
  they 
  are 
  acting, 
  or 
  are 
  capable 
  of 
  acting, 
  upon 
  the 
  retina 
  of 
  the 
  

   eye, 
  and 
  moreover 
  only 
  if 
  the 
  resulting 
  stimulation 
  of 
  the 
  optic 
  re- 
  

   ceptors 
  is 
  followed 
  by 
  a 
  nerve 
  current 
  set 
  up 
  in 
  the 
  optic 
  fibers 
  and 
  

   even 
  then 
  only 
  if 
  this 
  current 
  is 
  permitted 
  to 
  flow 
  into 
  the 
  higher 
  

   nerve 
  centers 
  of 
  the 
  cerebral 
  cortex. 
  A 
  still 
  closer 
  study 
  of 
  the 
  facts 
  

   shows 
  that 
  the 
  intraorganic 
  factors 
  in 
  this 
  process 
  are 
  apparently 
  

   more 
  essential 
  than 
  are 
  the 
  stimuli 
  which 
  constitute 
  the 
  physicist's 
  

   substitute 
  for 
  color. 
  The 
  actual 
  colors 
  which 
  are 
  aroused 
  by 
  given 
  

   stimuli 
  depend 
  radically 
  upon 
  the 
  condition 
  and 
  the 
  biological 
  type 
  

   of 
  the 
  stimulated 
  nervous 
  system, 
  and 
  conditions 
  are 
  readily 
  found 
  

   under 
  which 
  colors 
  appear 
  in 
  the 
  entire 
  absence 
  of 
  a 
  sensory 
  stimulus, 
  

   and 
  indeed 
  even 
  without 
  the 
  assistance 
  of 
  any 
  current 
  within 
  the 
  

   optic 
  nerves. 
  What 
  is 
  true 
  of 
  color 
  in 
  these 
  respects 
  holds 
  equally 
  

   for 
  all 
  other 
  sensory 
  qualities. 
  But 
  this 
  is 
  not 
  all. 
  The 
  same 
  con- 
  

   siderations 
  appear 
  to 
  apply 
  also 
  to 
  the 
  primary 
  qualities 
  of 
  space, 
  

   mass 
  and 
  time 
  in 
  so 
  far 
  as 
  they 
  are 
  given 
  in 
  the 
  immediate 
  experience 
  

   of 
  any 
  individual. 
  In 
  a 
  word, 
  immediate 
  experience 
  in 
  its 
  totality 
  is 
  

   determined 
  by 
  the 
  operations 
  of 
  the 
  nervous 
  system. 
  

  

  The 
  typical 
  plan 
  of 
  a 
  nervous 
  process 
  is 
  that 
  of 
  what 
  we 
  may 
  call 
  

   the 
  response 
  arc. 
  Physically 
  considered, 
  neuro-muscular 
  response 
  

   is 
  merely 
  a 
  special, 
  very 
  intricate, 
  example 
  of 
  the 
  propagation 
  of 
  physical 
  

   disturbances 
  along 
  a 
  restricted 
  conduction 
  path. 
  The 
  process 
  con- 
  

   sists 
  of 
  a 
  series 
  of 
  stages 
  following 
  each 
  other 
  in 
  space 
  and 
  in 
  time, 
  

   each 
  depending 
  for 
  its 
  exact 
  character 
  in 
  part 
  upon 
  the 
  nature 
  of 
  its 
  

   predecessor 
  and 
  in 
  part 
  upon 
  the 
  particular 
  elements 
  in 
  the 
  nervous 
  

   mechanism 
  which 
  are 
  carrying 
  it. 
  The 
  characteristic 
  successive 
  

   stages 
  of 
  a 
  response 
  process 
  may 
  be 
  listed 
  as 
  follows: 
  (1) 
  the 
  physical 
  

   object, 
  (2) 
  the 
  stimulus, 
  (3) 
  the 
  sense 
  organ 
  process, 
  (4) 
  the 
  receptor 
  

   process, 
  (5) 
  the 
  afferent 
  nerve 
  stimulation, 
  (6) 
  the 
  afferent 
  nerve 
  

   conduction, 
  (7) 
  the 
  central 
  synaptic 
  process, 
  (8) 
  the 
  efferent 
  nerve 
  

   conduction, 
  (9) 
  the 
  end 
  plate 
  process, 
  (10) 
  the 
  effector 
  process, 
  (11) 
  

   the 
  effect. 
  This 
  chain 
  of 
  events, 
  starting 
  with 
  the 
  environment 
  and 
  

   leading 
  back 
  to 
  it 
  again, 
  is 
  conceived 
  to 
  be 
  physically 
  complete, 
  at 
  

   no 
  point 
  involving 
  the 
  intervention 
  of 
  any 
  psychical 
  activity. 
  

  

  Now 
  it 
  happens 
  that 
  at 
  the 
  present 
  time 
  there 
  is 
  a 
  slight 
  disagree- 
  

  

  