﻿CAMOUFLAGE 
  — 
  FRIEDMAN 
  N 
  267 
  

  

  short 
  review, 
  our 
  interest 
  in 
  the 
  present 
  paper 
  being 
  in 
  what 
  happens 
  

   rather 
  than 
  in 
  how 
  it 
  is 
  caused. 
  Longley 
  found 
  that 
  reef 
  fishes 
  effect 
  

   rapid 
  color 
  adjustment 
  following 
  vertical 
  movements 
  — 
  some 
  species 
  

   change 
  from 
  the 
  decidedly 
  patterned 
  colors 
  that 
  they 
  wear 
  when 
  on 
  the 
  

   bottom 
  (and 
  can 
  be 
  seen 
  only 
  from 
  above) 
  to 
  a 
  uniform 
  coloration 
  

   when 
  rising 
  upward 
  through 
  deep 
  water 
  (where 
  a 
  bottom-approxi- 
  

   mating 
  pattern 
  would 
  be 
  revealing 
  rather 
  than 
  concealing). 
  Another 
  

   important 
  result 
  on 
  Longley's 
  work 
  is 
  the 
  demonstration 
  that 
  parti- 
  

   cular 
  phases 
  of 
  color 
  pattern 
  are 
  frequently 
  correlated 
  with 
  definite 
  

   types 
  of 
  activity 
  in 
  a 
  manner 
  which 
  is 
  in 
  keeping 
  with 
  what 
  seems 
  to 
  

   result 
  in 
  optical 
  illusion 
  (Year 
  Book 
  Carnegie 
  Institution 
  of 
  Washing- 
  

   ton, 
  vol. 
  27, 
  pp. 
  158-163, 
  1918). 
  For 
  example, 
  different 
  fishes 
  which 
  

   have 
  — 
  

  

  * 
  * 
  * 
  alternate 
  costumes 
  of 
  longitudinal 
  stripes 
  or 
  uniform 
  color, 
  and 
  of 
  

   transverse 
  bai's, 
  wear 
  the 
  former 
  when 
  in 
  motion 
  (an 
  arrangement 
  which 
  makes 
  

   for 
  concealment 
  in 
  that 
  it 
  tends 
  to 
  mask 
  forward 
  movement) 
  and 
  the 
  latter 
  when 
  

   at 
  rest 
  (when 
  bars 
  better 
  serve 
  to 
  break 
  up 
  the 
  contour 
  and 
  surface 
  form 
  against 
  

   a 
  broken 
  background). 
  Moreover, 
  precisely 
  similar 
  adjustments 
  are 
  found 
  in 
  

   certain 
  squids, 
  which 
  wear 
  stripes 
  for 
  swimming 
  and 
  bands 
  for 
  resting 
  [ex. 
  

   Cott, 
  Adaptive 
  Coloration 
  in 
  Animals, 
  p. 
  28, 
  1940]. 
  

  

  Other 
  examples 
  of 
  rapid 
  color 
  change 
  have 
  been 
  recorded 
  for 
  other 
  

   groups 
  of 
  animals 
  — 
  crustaceans, 
  cephalopods, 
  etc., 
  but 
  the 
  important 
  

   fact 
  in 
  the 
  present 
  connection 
  is 
  that 
  beneath 
  all 
  the 
  diversity 
  of 
  ana- 
  

   tomical 
  and 
  physiological 
  mechanisms 
  involved 
  in 
  these 
  different 
  

   animals 
  there 
  is 
  usually 
  a 
  common 
  type 
  of 
  external 
  stimulus 
  (change 
  in 
  

   immediate 
  environment 
  as 
  far 
  as 
  color, 
  texture, 
  etc., 
  is 
  concerned) 
  and 
  

   a 
  common 
  type 
  of 
  response. 
  

  

  Slower 
  responses 
  of 
  similar 
  type 
  are 
  known 
  in 
  certain 
  insects 
  and 
  

   spiders. 
  Poulton 
  (Philos. 
  Trans. 
  Roy. 
  Soc. 
  London, 
  vol. 
  178, 
  pp. 
  

   311-441, 
  1887) 
  showed 
  by 
  experimental 
  studies 
  that 
  the 
  larvae 
  and 
  

   pupae 
  of 
  certain 
  butterflies 
  possess 
  the 
  power 
  of 
  acquiring 
  the 
  color- 
  

   ation 
  of 
  their 
  immediate 
  surroundings 
  and 
  showed 
  that 
  in 
  species 
  of 
  

   Vanessa 
  and 
  Pieris 
  the 
  pupal 
  adjustment 
  was 
  due 
  to 
  extreme 
  sen- 
  

   sibility 
  of 
  the 
  larvae 
  to 
  reflected 
  light 
  during 
  the 
  final 
  resting 
  position 
  

   prior 
  to 
  pupation. 
  

  

  Aside 
  from 
  obliterative 
  shading 
  and 
  color 
  resemblance 
  many 
  animals 
  

   are 
  still 
  further 
  concealed 
  by 
  the 
  fact 
  that 
  the 
  patterns 
  of 
  their 
  

   coloration 
  tend 
  to 
  break 
  up 
  their 
  outlines, 
  so 
  that 
  at 
  a 
  distance 
  they 
  

   seem 
  to 
  be 
  bits 
  of 
  the 
  general 
  surroundings 
  rather 
  than 
  a 
  recognizable 
  

   shape 
  which 
  would 
  tend 
  to 
  reveal 
  them. 
  This 
  type 
  of 
  marking 
  is 
  

   known 
  as 
  — 
  

  

  DISRUPTIVE 
  COLORATION 
  

  

  Even 
  with 
  better 
  than 
  average 
  color 
  resemblance 
  and 
  with 
  some 
  

   countershading, 
  an 
  animal 
  is 
  recognizable 
  frequently 
  by 
  the 
  fact 
  that 
  it 
  

   presents 
  a 
  continuity 
  of 
  surface 
  enclosed 
  by 
  an 
  easily 
  identified 
  contour 
  

  

  