﻿ANIMAL 
  BEHAVIOUR 
  183 
  

  

  there 
  is 
  no 
  further 
  obstacle 
  to 
  progress. 
  In 
  this 
  direction 
  it 
  

   continues. 
  Through 
  systematically 
  testing 
  the 
  surroundings, 
  

   by 
  swinging 
  the 
  anterior 
  end 
  in 
  a 
  circle, 
  and 
  through 
  per- 
  

   forming 
  the 
  entire 
  reaction 
  repeatedly, 
  the 
  infusorian 
  is 
  

   bound 
  in 
  time 
  to 
  find 
  any 
  existing 
  egress 
  from 
  the 
  difficulties 
  

   even 
  though 
  it 
  be 
  but 
  a 
  narrow 
  and 
  tortuous 
  passageway 
  ' 
  

   (Jennings, 
  1906, 
  p. 
  49). 
  

  

  The 
  behaviour 
  of 
  Paramecium 
  is 
  very 
  instructive 
  in 
  its 
  

   combination 
  of 
  effectiveness 
  and 
  simplicity. 
  It 
  drives 
  itself 
  

   forward 
  in 
  a 
  narrow 
  spiral, 
  revolving 
  on 
  its 
  long 
  axis 
  and 
  

   swerving 
  a 
  little 
  towards 
  the 
  aboral 
  side 
  such 
  is 
  its 
  

   action 
  system 
  ; 
  and 
  most 
  of 
  its 
  behaviour 
  consists 
  of 
  slight 
  

   variations 
  on 
  this 
  simple 
  tune. 
  " 
  It 
  constantly 
  feels 
  its 
  way 
  

   about, 
  trying 
  in 
  a 
  systematic 
  way 
  all 
  sorts 
  of 
  conditions, 
  

   and 
  retiring 
  from 
  those 
  that 
  are 
  harmful. 
  Its 
  behaviour 
  

   is 
  in 
  principle 
  much 
  like 
  that 
  of 
  a 
  blind 
  and 
  deaf 
  person, 
  

   or 
  one 
  that 
  feels 
  his 
  way 
  about 
  in 
  the 
  dark. 
  It 
  is 
  a 
  con- 
  

   tinual 
  process 
  of 
  proving 
  all 
  things 
  and 
  holding 
  to 
  that 
  

   which 
  is 
  good' 
  (Jennings, 
  1906, 
  p. 
  106). 
  

  

  " 
  The 
  behaviour 
  and 
  reactions 
  of 
  Paramecium 
  consist 
  on 
  

   the 
  whole 
  in 
  performing 
  movements 
  which 
  subject 
  the 
  or- 
  

   ganism 
  to 
  varied 
  conditions 
  (using 
  this 
  word 
  in 
  the 
  widest 
  

   sense), 
  with 
  rejection 
  of 
  certain 
  of 
  these 
  conditions, 
  and 
  

   retention 
  of 
  others. 
  It 
  may 
  be 
  characterized 
  briefly 
  as 
  a 
  

   selection 
  from 
  among 
  the 
  varied 
  conditions 
  brought 
  about 
  

   by 
  varied 
  movements' 
  (Jennings, 
  1906, 
  p. 
  108). 
  On 
  the 
  

   whole 
  the 
  animalcule 
  rejects 
  or 
  avoids 
  what 
  is 
  injurious 
  and 
  

   accepts 
  or 
  seeks 
  what 
  is 
  beneficial, 
  just 
  as 
  higher 
  animals 
  

   and 
  men 
  do. 
  The 
  behaviour 
  is 
  adaptive 
  and 
  purposive. 
  In- 
  

   deed 
  Jennings 
  goes 
  the 
  length 
  of 
  saying 
  : 
  " 
  In 
  no 
  other 
  group 
  

   of 
  organisms 
  does 
  the 
  method 
  of 
  trial 
  and 
  error 
  so 
  completely 
  

   dominate 
  behaviour, 
  perhaps, 
  as 
  in 
  the 
  Infusoria." 
  

  

  