﻿162 
  THE 
  UNIQUENESS 
  OF 
  LIFE 
  

  

  is 
  in 
  part 
  determined 
  by 
  the 
  past 
  its 
  own 
  experience 
  and 
  

   the 
  history 
  of 
  its 
  race. 
  In 
  the 
  organism, 
  as 
  Bergson 
  says, 
  

   the 
  past 
  is 
  prolonged 
  into 
  the 
  present. 
  " 
  Living 
  things 
  

   therefore 
  require 
  an 
  historical 
  explanation. 
  Non-living 
  

   things, 
  on 
  the 
  contrary, 
  have 
  no 
  history 
  in 
  the 
  biological 
  

   sense 
  of 
  the 
  word, 
  and 
  no 
  inorganic 
  thing 
  carries 
  its 
  past 
  

   about 
  with 
  it' 
  (Russell, 
  1911, 
  p. 
  338). 
  We 
  have 
  to 
  pass, 
  

   therefore, 
  to 
  a 
  new 
  level 
  of 
  explanation, 
  and 
  whenever 
  we 
  

   mention 
  that 
  the 
  eel 
  is 
  one 
  of 
  a 
  deep-sea 
  race 
  which 
  has 
  

   adventurously 
  taken 
  to 
  colonising 
  the 
  fresh 
  waters 
  just 
  as 
  

   the 
  salmon 
  is 
  one 
  of 
  a 
  fresh-water 
  race 
  which 
  has 
  taken 
  to 
  

   exploiting 
  the 
  resources 
  of 
  the 
  sea, 
  and 
  notice 
  further 
  that 
  

   many 
  animals 
  return 
  to 
  their 
  birth-place 
  to 
  breed, 
  and 
  that 
  

   some 
  go 
  back 
  to 
  their 
  birth-place 
  to 
  die, 
  a 
  biological 
  light 
  

   begins 
  to 
  be 
  shed 
  on 
  the 
  eel's 
  strange 
  story. 
  And 
  we 
  have 
  

   but 
  begun. 
  Of 
  course 
  if 
  the 
  objector 
  is 
  prepared 
  to 
  main- 
  

   tain 
  that 
  the 
  enregistering 
  of 
  experience 
  by 
  organisms 
  is 
  

   nothing 
  more 
  than 
  a 
  special 
  case 
  of 
  the 
  peculiar 
  way 
  in 
  which 
  

   colloids 
  are 
  influenced 
  by 
  their 
  history, 
  we 
  can 
  only 
  say 
  that 
  

   this 
  theory 
  must 
  get 
  more 
  facts 
  to 
  back 
  it 
  before 
  we 
  can 
  take 
  

   it 
  very 
  seriously. 
  

  

  No 
  one 
  wishes 
  to 
  slacken 
  investigation 
  into 
  the 
  physiology 
  

   of 
  migration 
  a 
  most 
  fascinating 
  and 
  suggestive 
  inquiry. 
  

   It 
  is 
  known 
  that 
  when 
  eels 
  become 
  mature 
  there 
  is 
  an 
  altera- 
  

   tion 
  in 
  the 
  metabolism, 
  and 
  that 
  the 
  altered 
  metabolism 
  af- 
  

   fects 
  the 
  carbon 
  dioxide 
  content 
  of 
  the 
  blood, 
  that 
  this 
  in- 
  

   creases 
  irritability, 
  and 
  that 
  this 
  increases 
  range 
  and 
  vigour 
  

   of 
  movements, 
  and, 
  moreover, 
  that 
  changes 
  in 
  the 
  metabolism 
  

   of 
  the 
  animal 
  affect 
  its 
  reactions 
  to 
  chemicals 
  in 
  the 
  water, 
  

   to 
  gravity, 
  and 
  to 
  currents. 
  Much 
  knowledge 
  of 
  this 
  kind 
  is 
  

   accumulating, 
  but 
  it 
  seems 
  to 
  many 
  that 
  it 
  does 
  not 
  grip 
  the 
  

   problem 
  unless 
  it 
  be 
  taken 
  along 
  with 
  the 
  concept 
  of 
  the 
  

  

  