﻿Mr. 
  S. 
  B. 
  J. 
  Skertchly 
  on 
  Butterflies' 
  Enemies. 
  481 
  

  

  secreting 
  a 
  nauseous 
  fluid, 
  (c) 
  that 
  other 
  butterflies 
  

   noticed 
  this 
  immunity, 
  (d) 
  that 
  they 
  copied 
  it. 
  

  

  4. 
  It 
  would 
  be 
  of 
  comparatively 
  little 
  use 
  to 
  an 
  insect 
  to 
  

   be 
  unpalatable 
  if 
  the 
  insect 
  were 
  killed 
  in 
  being 
  tasted. 
  

   Hence 
  these 
  forms 
  have 
  very 
  strong 
  vitality. 
  

  

  5. 
  Protective 
  resemblance 
  being 
  almost 
  universal 
  shows 
  

   a 
  strong 
  sense 
  of 
  danger. 
  

  

  6. 
  Being 
  generally 
  confined 
  to 
  the 
  under 
  surface 
  it 
  

   ensures 
  protection 
  during 
  the 
  period 
  of 
  rest. 
  In 
  this 
  

   it 
  differs 
  radically 
  from 
  mimicry. 
  

  

  V. 
  Mimicry's 
  Raison 
  d'etre. 
  

  

  Mimicry 
  we 
  have 
  suggested 
  is 
  a 
  protection 
  against 
  foes 
  

   which 
  attack 
  butterflies 
  upon 
  the 
  wing. 
  I 
  take 
  it 
  that 
  the 
  

   amount 
  of 
  danger 
  may 
  be 
  measured 
  by 
  the 
  pains 
  taken 
  to 
  

   avoid 
  it. 
  On 
  this 
  principle 
  butterflies 
  are 
  in 
  much 
  greater 
  

   peril 
  when 
  resting 
  than 
  when 
  on 
  the 
  wing 
  ; 
  otherwise 
  

   mimicry 
  would 
  be 
  as 
  common 
  as 
  protective 
  resemblance. 
  

  

  The 
  only 
  foes 
  worthy 
  of 
  such 
  efforts 
  as 
  are 
  displayed 
  in 
  

   mimicry 
  are 
  birds. 
  Lizards, 
  snakes, 
  and 
  monkeys 
  may 
  occa- 
  

   sionally 
  snatch 
  a 
  butterfly, 
  but 
  birds 
  must 
  always 
  have 
  been 
  

   the 
  chief 
  foes. 
  Yet 
  we 
  have 
  seen 
  that 
  butterfly-eating 
  birds 
  

   form 
  a 
  very 
  small 
  minority 
  both 
  in 
  species 
  and 
  individuals 
  in 
  

   the 
  avifauna 
  of 
  the 
  world. 
  

  

  Insectivorous 
  birds 
  vary 
  much 
  in 
  their 
  habits. 
  At 
  one 
  end 
  

   of 
  the 
  scale 
  the 
  woodpeckers 
  and 
  creepers 
  fish 
  insects 
  out 
  of 
  

   holes, 
  at 
  the 
  other 
  end 
  swallows 
  and 
  swifts 
  catch 
  all 
  their 
  food 
  

   upon 
  the 
  wing. 
  Between 
  these 
  tits 
  hunt 
  over 
  branches, 
  

   warblers 
  flit 
  among 
  the 
  leaves, 
  flycatchers 
  make 
  short 
  darts 
  

   at 
  passing 
  flies. 
  Moreover, 
  birds 
  are 
  capable 
  of 
  profound 
  

   modification 
  of 
  structure 
  and 
  habit, 
  as 
  in 
  the 
  case 
  of 
  swifts 
  

   transformed 
  into 
  humming-birds. 
  

  

  Now 
  I 
  suggest 
  that, 
  as 
  shyness 
  and 
  mimicry 
  are 
  proofs 
  of 
  

   a 
  sense 
  of 
  danger 
  from 
  moving 
  foes, 
  and 
  as 
  the 
  effort 
  so 
  dis- 
  

   played 
  is 
  disproportionate 
  to 
  the 
  danger 
  as 
  existing 
  at 
  present, 
  

   it 
  may 
  be 
  that 
  formerly 
  butterfly-catching 
  birds 
  were 
  more 
  

   plentiful 
  than 
  now 
  ; 
  in 
  other 
  words, 
  that 
  shyness 
  and 
  mimicry 
  

   are 
  habits 
  acquired 
  long 
  since 
  which 
  have 
  survived 
  the 
  neces- 
  

   sity 
  that 
  gave 
  tnem 
  birth. 
  

  

  This 
  supposes 
  a 
  change 
  in 
  the 
  habits 
  of 
  many 
  insectivorous 
  

   birds. 
  Such 
  a 
  change 
  may 
  have 
  been 
  assisted 
  by 
  the 
  obvious 
  

   fact 
  that 
  a 
  butterfly, 
  looked 
  upon 
  as 
  food, 
  is 
  so 
  much 
  more 
  

   chaff 
  than 
  grain 
  — 
  his 
  edible 
  body 
  so 
  sjnall, 
  his 
  ummtritious 
  

   \vings 
  so 
  large. 
  He 
  must 
  be 
  troublesome 
  to 
  catch, 
  very 
  un- 
  

  

  