﻿ANIMAL 
  BEHAVIOUR 
  185 
  

  

  mal, 
  and 
  the 
  modifications 
  are 
  regulatory, 
  not 
  haphazard, 
  

   in 
  character. 
  The 
  phenomena 
  are 
  thus 
  similar 
  to 
  those 
  shown 
  

   in 
  the 
  ' 
  learning 
  7 
  of 
  higher 
  organisms, 
  save 
  that 
  the 
  modifica- 
  

   tions 
  depend 
  upon 
  less 
  complex 
  relations 
  and 
  last 
  a 
  shorter 
  

   time' 
  (p. 
  179). 
  Our 
  view 
  of 
  living 
  creatures 
  must 
  make 
  

   room 
  for 
  the 
  new 
  fact 
  that 
  behaviour 
  reaches 
  this 
  level 
  among 
  

   the 
  unicellulars. 
  

  

  Among 
  unicellulars, 
  then, 
  we 
  see 
  the 
  beginning 
  of 
  explor- 
  

   ing 
  and 
  testing, 
  the 
  beginning 
  of 
  actual 
  ' 
  hunting 
  ', 
  and 
  this 
  

   is 
  on 
  the 
  main 
  line 
  of 
  advance. 
  We 
  see, 
  also, 
  the 
  enregis- 
  

   tration 
  of 
  particular 
  reactions 
  to 
  stimuli, 
  an 
  organisation 
  of 
  

   behaviour 
  that 
  is 
  economical 
  and 
  in 
  its 
  rapidity 
  of 
  response 
  

   often 
  life-saving. 
  But 
  we 
  see, 
  also, 
  a 
  selection 
  of 
  reactions, 
  

   a 
  trying 
  of 
  one 
  after 
  the 
  other 
  till 
  haply 
  one 
  meets 
  the 
  needs 
  

   of 
  the 
  case, 
  and 
  this 
  ' 
  trial-and-error 
  ' 
  method 
  is 
  likewise 
  

   on 
  the 
  mp.in 
  line 
  of 
  advance. 
  

  

  4. 
  Special 
  Case 
  of 
  Shell-building 
  among 
  Arenaceous 
  

  

  Foraminifera. 
  

  

  In 
  the 
  shell-building 
  of 
  some 
  of 
  the 
  so-called 
  arenaceous 
  

   Foraminifera 
  Mr. 
  E. 
  A. 
  Heron- 
  Allen 
  and 
  Mr. 
  A. 
  Earland 
  

   have 
  described 
  (1915) 
  what 
  looks 
  like 
  constructive 
  skill 
  in 
  

   the 
  use 
  of 
  materials. 
  As 
  every 
  one 
  knows, 
  many 
  unicellular 
  

   animals 
  secrete 
  shells 
  of 
  exquisite 
  beauty, 
  the 
  ' 
  organic 
  crys- 
  

   tallisation 
  ? 
  of 
  which 
  is 
  as 
  much 
  of 
  an 
  unsolved 
  problem 
  as 
  

   the 
  adaptive 
  internal 
  architecture 
  of 
  bones, 
  but 
  in 
  the 
  case 
  

   of 
  the 
  arenaceous 
  Foraminifera 
  the 
  building 
  materials 
  are 
  

   found 
  ready-made 
  in 
  the 
  environment 
  and 
  are 
  utilised 
  very 
  

   effectively 
  to 
  form 
  a 
  casing. 
  The 
  points 
  of 
  special 
  interest 
  

   are 
  two,--(l) 
  that 
  a 
  particular 
  kind 
  of 
  material, 
  such 
  as 
  

   sponge-spicules, 
  is 
  selected 
  from 
  the 
  surrounding 
  debris, 
  from 
  

  

  