﻿264 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  grass, 
  for 
  example, 
  each 
  blade 
  (when 
  close 
  up) 
  has 
  a 
  shadow, 
  or 
  at 
  

   least 
  an 
  outline 
  ; 
  fallen 
  twigs 
  or 
  leaves 
  present 
  even 
  more 
  shapes 
  and 
  

   irregularities 
  of 
  light 
  and 
  dark. 
  The 
  combination 
  of 
  countershading 
  

   and 
  pattern 
  resemblance 
  does 
  result, 
  however, 
  in 
  something 
  similar 
  

   to 
  blended 
  patterns, 
  but, 
  however, 
  functions 
  also, 
  and 
  in 
  many 
  instances 
  

   chiefly, 
  at 
  close 
  range. 
  Having 
  now 
  grasped 
  the 
  role 
  played 
  by 
  obliter- 
  

   ative 
  shading, 
  we 
  may 
  proceed 
  to 
  examine 
  the 
  varieties 
  of 
  patterns 
  

   and 
  color 
  arrangements 
  found 
  in 
  animals 
  which 
  are 
  concealingly 
  

   colored. 
  

  

  COLOR 
  RESEMBLANCE 
  

  

  Most 
  of 
  us 
  have 
  at 
  one 
  time 
  or 
  another 
  become 
  aware 
  of 
  a 
  general 
  

   similarity 
  in 
  appearance 
  between 
  certain 
  animals 
  and 
  their 
  surround- 
  

   ings. 
  We 
  have 
  come 
  to 
  expect 
  creatures 
  living 
  in 
  deserts 
  or 
  sandy 
  

   places 
  to 
  have 
  pale 
  or 
  sandy 
  hues 
  and 
  not 
  to 
  startle 
  us 
  with 
  the 
  bril- 
  

   liant 
  greens 
  and 
  reds 
  of 
  some 
  of 
  the 
  denizens 
  of 
  dense 
  tropical 
  forests. 
  

   Without 
  asking 
  ourselves 
  why 
  or 
  even 
  consciously 
  wondering, 
  we 
  con- 
  

   nect 
  the 
  white 
  of 
  the 
  polar 
  bear 
  and 
  of 
  the 
  snowy 
  owl 
  with 
  the 
  snow 
  and 
  

   ice 
  of 
  their 
  Arctic 
  habitat. 
  Again 
  it 
  must 
  be 
  emphasized 
  that 
  not 
  all 
  

   animals 
  are 
  colored 
  to 
  resemble 
  part 
  of 
  their 
  environment; 
  but 
  the 
  

   fact 
  that 
  exceptions 
  are 
  easy 
  to 
  find 
  should 
  not 
  minimize 
  the 
  other 
  

   fact 
  that 
  a 
  very 
  great 
  many 
  animals 
  of 
  all 
  groups 
  and 
  living 
  in 
  all 
  parts 
  

   of 
  the 
  world 
  and 
  in 
  all 
  kinds 
  of 
  surroundings 
  do 
  bear 
  on 
  their 
  coats 
  a 
  

   resemblance 
  to 
  their 
  immediate 
  environment. 
  

  

  General 
  color 
  resemblance, 
  of 
  necessarily 
  only 
  moderate 
  value 
  in 
  

   effecting 
  concealment, 
  is 
  shown 
  by 
  the 
  preponderance 
  of 
  green 
  birds, 
  

   green 
  tree 
  toads, 
  tree 
  snakes, 
  arboreal 
  insects, 
  etc., 
  in 
  the 
  forested 
  parts 
  

   of 
  the 
  world, 
  with 
  a 
  similarly 
  large 
  number 
  of 
  brownish 
  forms 
  

   dwelling 
  on 
  or 
  in 
  the 
  forest 
  floor. 
  The 
  common 
  salt-and-pepper 
  

   mottling 
  or 
  grayish-brown 
  washes 
  of 
  shore 
  birds 
  show 
  a 
  general 
  re- 
  

   semblance 
  to 
  their 
  sandy 
  or 
  pebbly 
  habitat. 
  The 
  whole 
  question 
  of 
  

   color 
  resemblance 
  is 
  still 
  unfortunately 
  largely 
  couched 
  in 
  terms 
  of 
  

   human 
  color 
  vision. 
  This 
  will 
  have 
  to 
  be 
  altered 
  with 
  increasing 
  

   knowledge 
  of 
  the 
  color 
  vision 
  of 
  the 
  enemies 
  of 
  each 
  animal 
  showing 
  

   color 
  resemblance 
  to 
  its 
  background. 
  An 
  example 
  may 
  help 
  clarify 
  

   this 
  point. 
  It 
  is 
  known 
  that 
  modern 
  developments 
  in 
  infrared 
  pho- 
  

   tography 
  have 
  revealed 
  that 
  different 
  green 
  animals 
  differ 
  greatly 
  in 
  

   their 
  absorption 
  of 
  infrared 
  light, 
  and 
  consequently 
  those 
  with 
  great 
  

   absorptive 
  properties 
  photograph 
  as 
  dark 
  objects 
  and 
  those 
  that 
  

   reflect 
  (and 
  do 
  not 
  absorb) 
  the 
  infrared 
  come 
  out 
  as 
  light 
  objects 
  in 
  

   the 
  photographs. 
  It 
  is 
  suspected 
  that 
  some 
  predaceous 
  animals, 
  such 
  

   as 
  certain 
  owls, 
  have 
  a 
  visual 
  range 
  beyond 
  the 
  human 
  one 
  on 
  the 
  

   infrared 
  end 
  of 
  the 
  spectrum. 
  It 
  would 
  follow 
  from 
  this 
  that 
  some 
  

   green 
  animals 
  might 
  be 
  seen 
  readily 
  by 
  the 
  owls 
  while 
  others 
  would 
  

  

  