﻿Dr. 
  H. 
  Eltringham 
  on 
  Butterfly 
  Vision. 
  43 
  

  

  yellow 
  Composite 
  with 
  a 
  nearly 
  black 
  centre, 
  and 
  one 
  of 
  the 
  

   most 
  conspicuous 
  flowers 
  in 
  the 
  border. 
  In 
  connection 
  

   with 
  this 
  flower 
  I 
  discovered 
  a 
  very 
  remarkable 
  fact. 
  Forel 
  , 
  

   in 
  remarking 
  that 
  insects 
  are 
  rarely 
  deceived 
  by 
  artificial 
  

   flowers, 
  suggests 
  that 
  what 
  appear 
  to 
  be 
  close 
  imitations 
  

   to 
  us 
  have 
  a 
  different 
  appearance 
  to 
  the 
  insect's 
  eye, 
  and 
  

   colours 
  which 
  we 
  should 
  match 
  appear 
  different 
  to 
  them. 
  

   I 
  investigated 
  this 
  point 
  by 
  means 
  of 
  photography, 
  and 
  

   whilst 
  artificial 
  roses, 
  violets, 
  etc. 
  , 
  all 
  affected 
  a 
  photographic 
  

   plate 
  in 
  the 
  same 
  way 
  as 
  the 
  real 
  flowers, 
  the 
  Rudbeckia 
  

   gave 
  an 
  entirely 
  different 
  appearance 
  in 
  a 
  non-screened 
  

   photograph 
  to 
  that 
  which 
  it 
  presents 
  to 
  our 
  eye. 
  

  

  In 
  the 
  unscreened 
  photograph 
  only 
  the 
  tips 
  of 
  the 
  petals 
  

   are 
  luminous, 
  the 
  rest 
  being 
  almost 
  as 
  black 
  as 
  the 
  centre. 
  

   I 
  found 
  no 
  other 
  flower 
  presenting 
  a 
  similar 
  peculiarity, 
  and 
  

   the 
  observation 
  is 
  merely 
  of 
  value 
  in 
  connection 
  with 
  the 
  

   appended 
  table 
  as 
  suggesting 
  that 
  the 
  flower 
  appears 
  as 
  

   conspicuous 
  to 
  the 
  butterflies 
  as 
  it 
  does 
  to 
  us, 
  and 
  that 
  their 
  

   sight 
  is 
  of 
  a 
  similar 
  nature. 
  With 
  the 
  exception 
  of 
  the 
  

   crimson 
  and 
  the 
  white, 
  the 
  flowers 
  most 
  visited, 
  according 
  

   to 
  my 
  observation, 
  were 
  those 
  which 
  were 
  most 
  conspicuous 
  

   to 
  our 
  eyes. 
  

  

  I 
  now 
  turned 
  my 
  attention 
  to 
  a 
  large 
  bed 
  of 
  asters, 
  the 
  

   colours 
  of 
  which 
  were 
  white, 
  three 
  shades 
  of 
  pink, 
  and 
  three 
  

   shades 
  of 
  purple. 
  Leaving 
  the 
  white 
  out 
  of 
  consideration, 
  

   for 
  reasons 
  already 
  stated, 
  it 
  may 
  be 
  remarked 
  that 
  the 
  

   purple 
  flowers 
  were 
  particularly 
  conspicuous 
  and 
  sharply 
  

   defined 
  on 
  their 
  green 
  background, 
  a 
  fact 
  due 
  not, 
  of 
  course, 
  

   to 
  their 
  luminosity 
  but 
  to 
  their 
  colour. 
  I 
  observed 
  the 
  

   choice 
  of 
  colour 
  in 
  427 
  instances, 
  and 
  these 
  were 
  divided 
  as 
  

   follows 
  : 
  — 
  

  

  White 
  .... 
  47 
  

   Pink 
  . 
  . 
  . 
  .135 
  

   Purple 
  . 
  . 
  . 
  .245 
  

  

  It 
  should 
  be 
  noted 
  that 
  the 
  pink 
  flowers 
  were 
  more 
  

   numerous 
  than 
  the 
  purple 
  in 
  the 
  proportion 
  of 
  about 
  four 
  

   to 
  three. 
  The 
  butterflies 
  were 
  mostly 
  V. 
  urticae, 
  but 
  io, 
  

   atalanta, 
  and 
  C. 
  -album 
  were 
  also 
  occasional 
  visitors. 
  

  

  On 
  the 
  assumption 
  that 
  the 
  preference 
  for 
  purple 
  is 
  due 
  

   to 
  the 
  fact 
  that 
  this 
  colour 
  is 
  more 
  conspicuous 
  and 
  that 
  the 
  

   purple 
  flowers 
  are 
  more 
  apt 
  to 
  " 
  catch 
  the 
  eye 
  " 
  of 
  the 
  insect, 
  

   I 
  proceeded 
  to 
  endeavour 
  to 
  analyse 
  the 
  conspicuousness 
  of 
  

   this 
  colour. 
  I 
  first 
  photographed 
  three 
  white, 
  three 
  pink, 
  

  

  