﻿ADAPTIVENESS 
  AND 
  PURPOSIVENESS 
  337 
  

  

  of 
  lining 
  the 
  interior 
  with 
  feathers 
  there 
  may 
  be 
  over 
  two 
  

   thousand 
  of 
  them, 
  of 
  covering 
  the 
  outside 
  with 
  lichens 
  

   which 
  make 
  the 
  nest 
  almost 
  invisible 
  on 
  the 
  bough. 
  There 
  

   is 
  no 
  doubt 
  as 
  to 
  the 
  adaptiveness 
  of 
  the 
  chain 
  of 
  acts 
  ; 
  it 
  

   seems 
  clear 
  that 
  the 
  work 
  is 
  without 
  justification 
  until 
  it 
  

   is 
  finished 
  ; 
  we 
  cannot 
  make 
  sense 
  of 
  the 
  prolonged 
  activity 
  

   unless 
  we 
  see 
  the 
  whole 
  in 
  the 
  light 
  of 
  the 
  final 
  result 
  which 
  

   is 
  of 
  great 
  value 
  to 
  the 
  individual 
  bird, 
  to 
  the 
  nestlings, 
  and 
  

   to 
  the 
  species 
  in 
  question. 
  But 
  we 
  are 
  no 
  'longer 
  so 
  certain 
  

   that 
  the 
  bird's 
  behaviour 
  is 
  actuated 
  by 
  perceived 
  purpose. 
  

   We 
  may 
  know, 
  for 
  instance, 
  that 
  the 
  bird 
  never 
  made 
  a 
  

   nest 
  or 
  laid 
  an 
  egg 
  before; 
  we 
  know 
  that 
  there 
  is 
  a 
  remark- 
  

   able 
  rigidity 
  in 
  the 
  routine 
  which 
  sometimes 
  detracts 
  from 
  

   its 
  effectiveness; 
  and 
  that 
  there 
  are 
  occasional 
  aberrations 
  

   which 
  suggest 
  that 
  the 
  bird 
  is 
  not 
  quite 
  on 
  the 
  spot. 
  In 
  

   other 
  words, 
  we 
  are 
  watching 
  an 
  instinctive 
  routine 
  with 
  a 
  

   spice 
  of 
  intelligence. 
  How 
  far 
  are 
  we 
  warranted 
  in 
  saying 
  

   that 
  it 
  is 
  actuated 
  by 
  purpose? 
  Can 
  there 
  be 
  purpose 
  which 
  

   is 
  not 
  clearly 
  perceived 
  ? 
  We 
  propose 
  to 
  rank 
  all 
  such 
  cases 
  

   under 
  the 
  rubric 
  ' 
  purposiveness 
  '. 
  It 
  implies 
  in 
  the 
  bird's 
  

   case 
  a 
  determined 
  endeavour, 
  obedience 
  to 
  an 
  inborn 
  inspira- 
  

   tion 
  modified 
  by 
  intelligence, 
  but 
  we 
  are 
  not 
  sure 
  how 
  far 
  

   the 
  end 
  is 
  in 
  view. 
  

  

  Returning 
  to 
  the 
  observations 
  of 
  Prof. 
  J. 
  B. 
  Watson 
  and 
  

   Dr. 
  K. 
  S. 
  Lashley 
  on 
  homing 
  terns, 
  we 
  have 
  to 
  interpret 
  such 
  

   facts 
  as 
  these. 
  A 
  number 
  of 
  brooding 
  terns 
  are 
  conveyed 
  in 
  

   hooded 
  cages 
  on 
  board 
  ship 
  for 
  over 
  four 
  hundred 
  miles 
  

   from 
  the 
  nesting 
  island 
  ; 
  they 
  are 
  liberated 
  in 
  the 
  middle 
  

   of 
  the 
  sea 
  beyond 
  all 
  hint 
  of 
  land 
  ; 
  they 
  set 
  off 
  at 
  once 
  for 
  

   home 
  against 
  a 
  head 
  wind 
  ; 
  some 
  of 
  them 
  reach 
  home 
  safely. 
  

   How 
  they 
  succeeded 
  we 
  do 
  not 
  know; 
  whether 
  they 
  are 
  in- 
  

   fluenced 
  by 
  magnetic 
  currents 
  and 
  the 
  like 
  we 
  do 
  not 
  know; 
  

  

  