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  ANIMAL 
  BEHAVIOUR 
  

  

  at 
  a 
  given 
  time 
  depends 
  on 
  past 
  experiences 
  on 
  former 
  ex- 
  

   ternal 
  conditions 
  and 
  on 
  former 
  actions. 
  

  

  Succession 
  of 
  Tentative 
  Reflexes. 
  Because 
  of 
  the 
  abun- 
  

   dance 
  of 
  reflexes 
  in 
  the 
  simpler 
  animals 
  the 
  impression 
  has 
  

   gained 
  ground 
  that 
  behaviour 
  in 
  these 
  lower 
  reaches 
  of 
  life 
  

   is 
  very 
  stereotyped. 
  But 
  this 
  impression 
  requires 
  critical 
  

   consideration. 
  When 
  a 
  particular 
  reflex 
  action 
  solves 
  a 
  par- 
  

   ticular 
  problem 
  at 
  a 
  stroke, 
  there 
  is 
  no 
  more 
  to 
  be 
  done. 
  

   But 
  the 
  problem 
  is 
  often 
  more 
  difficult, 
  and 
  what 
  the 
  creature 
  

   does 
  is 
  to 
  exhibit 
  varied 
  movements 
  and 
  to 
  select 
  certain 
  

   resulting 
  conditions. 
  Even 
  in 
  such 
  predominantly 
  reflex 
  

   creatures 
  as 
  sea-urchins, 
  the 
  tube-feet, 
  spines, 
  and 
  pedicel- 
  

   larise 
  may 
  in 
  difficult 
  situations 
  continue 
  in 
  varied 
  tentative 
  

   movements, 
  as 
  if 
  trying 
  all 
  expedients, 
  and 
  long 
  after 
  the 
  

   original 
  stimulation 
  has 
  ceased. 
  The 
  ' 
  righting 
  ? 
  reaction 
  

   of 
  an 
  ' 
  inverted 
  ' 
  starfish 
  is 
  singularly 
  varied 
  and 
  flexible. 
  

   Professor 
  Preyer 
  repeatedly 
  slipped 
  a 
  short 
  india-rubber 
  tube 
  

   over 
  one 
  of 
  the 
  arms 
  of 
  a 
  brittle 
  star, 
  and 
  observed 
  five 
  

   different 
  ways 
  in 
  which 
  it 
  was 
  removed, 
  including, 
  it 
  must 
  

   be 
  confessed, 
  as 
  one 
  desperate 
  method, 
  the 
  surrender 
  of 
  the 
  

   arm 
  itself. 
  As 
  the 
  observer 
  remarked, 
  " 
  If 
  one 
  method 
  does 
  

   not 
  help, 
  another 
  is 
  used." 
  

  

  Professor 
  Preyer's 
  experiments 
  on 
  pegging 
  down 
  starfishes 
  

   (of 
  course 
  without 
  injuring 
  them) 
  revealed 
  extraordinary 
  flex- 
  

   ibility 
  of 
  behaviour 
  and 
  also 
  a 
  shortening 
  of 
  the 
  time 
  required 
  

   for 
  escape. 
  The 
  number 
  of 
  useless 
  movements, 
  " 
  superfluous 
  

   twistings, 
  feelings 
  about, 
  and 
  forward 
  and 
  backward 
  mo- 
  

   tions 
  ", 
  becomes 
  less 
  the 
  oftener 
  the 
  individual 
  has 
  been 
  

   placed 
  in 
  such 
  a 
  situation. 
  If 
  this 
  is 
  true 
  (Prof. 
  Jennings 
  

   notes), 
  we 
  have 
  in 
  so 
  low 
  an 
  animal 
  as 
  the 
  starfish 
  regulation 
  

   through 
  the 
  selection 
  of 
  conditions 
  produced 
  by 
  varied 
  move- 
  

   ments 
  passing 
  into 
  a 
  more 
  directly 
  regulatory 
  action; 
  in 
  other 
  

  

  