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  ANIMAL 
  BEHAVIOUR 
  

  

  general 
  action, 
  just 
  as 
  in 
  animals 
  in 
  which 
  a 
  common 
  centre 
  

   produces 
  the 
  action." 
  As 
  von 
  Uexkiill 
  puts 
  it, 
  when 
  a 
  dog 
  

   runs, 
  the 
  animal 
  moves 
  its 
  legs; 
  when 
  a 
  sea-urchin 
  crawls, 
  

   the 
  legs 
  (spines) 
  move 
  the 
  animal. 
  

  

  The 
  astounding 
  fact 
  is 
  the 
  unification 
  of 
  behaviour 
  that 
  

   may 
  occur 
  in 
  such 
  a 
  " 
  republic 
  of 
  reflexes 
  ". 
  When 
  a 
  sea- 
  

   urchin 
  is 
  placed 
  upside 
  down, 
  a 
  continuation 
  of 
  all 
  the 
  usual 
  

   reactions 
  would 
  cause 
  it 
  to 
  move 
  on 
  in 
  an 
  inverted 
  position. 
  

   But 
  as 
  von 
  Uexkiill 
  has 
  shown, 
  the 
  unusual 
  physiological 
  

   state 
  induces 
  a 
  thoroughgoing 
  change 
  in 
  the 
  behaviour 
  of 
  the 
  

   spines, 
  they 
  depart 
  altogether 
  from 
  routine, 
  and 
  work 
  adap- 
  

   tively 
  to 
  the 
  needs 
  of 
  the 
  organism 
  as 
  a 
  whole, 
  the 
  animal 
  

   being 
  turned 
  right 
  again. 
  This 
  warns 
  us 
  not 
  to 
  think 
  of 
  

   reflexes 
  woodenly; 
  and 
  if 
  we 
  need 
  another 
  warning 
  we 
  

   may 
  get 
  it 
  in 
  the 
  extraordinarily 
  subtle 
  reflex 
  by 
  which 
  a 
  

   flatfish 
  adjusts 
  its 
  coloration 
  to 
  that 
  of 
  the 
  immediate 
  en- 
  

   vironment 
  of 
  shingle. 
  

  

  Reflex 
  Responses 
  are 
  Affected 
  ~by 
  the 
  Physiological 
  Con- 
  

   dition 
  of 
  the 
  Organism. 
  In 
  stinging 
  animals, 
  such 
  as 
  sea- 
  

   anemones 
  and 
  medusae, 
  there 
  are 
  numerous 
  reflex 
  actions 
  

   of 
  an 
  adaptive 
  kind, 
  concerned, 
  for 
  instance, 
  with 
  feeding. 
  

   But 
  it 
  has 
  been 
  shown 
  by 
  Professor 
  Jennings 
  and 
  others 
  that 
  

   the 
  reaction 
  is 
  not 
  simply 
  a 
  question 
  of 
  predetermined 
  struc- 
  

   ture 
  and 
  an 
  external 
  stimulus. 
  The 
  answer 
  depends 
  on 
  the 
  

   relation 
  of 
  external 
  conditions 
  to 
  internal 
  processes. 
  " 
  We 
  

   cannot 
  predict 
  how 
  an 
  animal 
  will 
  react 
  to 
  a 
  given 
  condition 
  

   unless 
  we 
  know 
  the 
  state 
  of 
  its 
  internal 
  physiological 
  proc- 
  

   esses 
  ' 
  (Jennings, 
  1906, 
  p. 
  231). 
  Thus, 
  to 
  take 
  a 
  simple 
  

   case, 
  a 
  sea-anemone 
  cheated 
  several 
  times 
  with 
  false 
  food 
  

   ceases 
  to 
  exhibit 
  the 
  normal 
  reflex. 
  Many 
  a 
  sea-anemone, 
  

   e.g., 
  the 
  large 
  Stoichactis 
  helianthus, 
  will 
  remove 
  food 
  from 
  

   the 
  oral 
  disc 
  if 
  it 
  is 
  not 
  hungry. 
  A 
  specimen 
  of 
  Metridium 
  

  

  