﻿Dr. 
  H. 
  Eltringham 
  on 
  Butterfly 
  Vision. 
  47 
  

  

  which 
  the 
  ewphrosyne 
  actually 
  settled. 
  Its 
  action 
  was 
  very 
  

   characteristic 
  ; 
  there 
  was 
  none 
  of 
  the 
  excited 
  flutter 
  which 
  

   always 
  accompanies 
  the 
  usual 
  amatory 
  advances, 
  but 
  a 
  

   direct 
  alighting 
  with 
  precision. 
  There 
  can 
  be 
  no 
  doubt 
  

   that 
  the 
  insect 
  had 
  mistaken 
  my 
  blue 
  model 
  for 
  a 
  bit 
  of 
  

   the 
  bugle 
  flower, 
  which 
  it 
  closely 
  matched 
  in 
  colour. 
  

  

  One 
  further 
  experiment 
  was 
  made 
  to 
  test 
  the 
  apparent 
  

   colour 
  sense 
  from 
  the 
  spectroscopic 
  point 
  of 
  view. 
  I 
  

   discovered 
  that 
  the 
  tawny 
  yellow 
  colour 
  of 
  the 
  real 
  butterfly 
  

   contained 
  many 
  green 
  rays, 
  and 
  also 
  that 
  the 
  dye 
  I 
  had 
  

   hitherto 
  used 
  was 
  spectroscopically 
  almost 
  the 
  same 
  as 
  

   the 
  ground 
  colour 
  of 
  the 
  insect. 
  I 
  therefore 
  sought 
  some 
  

   dye 
  which 
  would 
  give 
  me 
  a 
  visual 
  colour 
  resembling 
  the 
  

   real 
  butterfly, 
  but 
  spectroscopically 
  different. 
  I 
  found 
  

   this 
  in 
  " 
  Orange 
  G," 
  which 
  when 
  examined 
  with 
  a 
  set 
  of 
  

   colour 
  filters 
  appeared 
  to 
  reflect 
  no 
  green 
  at 
  all, 
  and 
  cer- 
  

   tainly 
  looked 
  quite 
  different 
  to 
  the 
  colour 
  of 
  the 
  real 
  butter- 
  

   fly. 
  I 
  dyed 
  a 
  bleached 
  eujphrosyne 
  with 
  this 
  and 
  repeated 
  

   my 
  experiments. 
  To 
  an 
  untreated 
  model 
  there 
  were 
  38 
  

   visits 
  ; 
  to 
  one 
  dyed 
  with 
  Orange 
  Gr, 
  14. 
  Allowing 
  for 
  the 
  

   more 
  natural 
  appearance 
  of 
  the 
  untreated 
  specimen, 
  the 
  

   observation 
  seems 
  to 
  show 
  that 
  the 
  yellow 
  which 
  to 
  my 
  

   eye 
  nearly 
  matched 
  the 
  real 
  butterfly, 
  though 
  spectroscopi- 
  

   cally 
  a 
  very 
  different 
  colour, 
  was 
  also 
  a 
  good 
  imitation 
  for 
  

   the 
  live 
  insect. 
  

  

  On 
  the 
  same 
  occasion 
  I 
  made 
  a 
  test 
  to 
  prove 
  that 
  scent, 
  

   however 
  lingering, 
  is 
  not 
  a 
  potent 
  factor 
  in 
  guiding 
  the 
  

   butterfly, 
  at 
  least 
  in 
  the 
  early 
  stages 
  of 
  courtship. 
  I 
  put 
  

   up 
  a 
  specimen 
  of 
  B. 
  selene, 
  a 
  very 
  similar 
  butterfly 
  of 
  a 
  

   different 
  species, 
  and 
  it 
  gained 
  15 
  visits. 
  

  

  In 
  the 
  course 
  of 
  these 
  experiments 
  I 
  took 
  occasion 
  to 
  

   observe 
  the 
  distance 
  at 
  which 
  one 
  butterfly 
  appeared 
  to 
  

   become 
  visually 
  conscious 
  of 
  the 
  presence 
  of 
  another, 
  and 
  

   I 
  gained 
  the 
  impression 
  that 
  for 
  this 
  species 
  the 
  limit 
  was 
  

   about 
  3| 
  feet. 
  The 
  distance 
  is 
  greater 
  when 
  both 
  insects 
  

   are 
  flying. 
  If 
  one 
  is 
  at 
  rest 
  another 
  flying 
  past 
  has 
  to 
  come 
  

   closer 
  before 
  it 
  perceives 
  it. 
  A 
  euphrosyne 
  will 
  pursue 
  

   another 
  species 
  of 
  butterfly 
  on 
  the 
  wing 
  if 
  the 
  other 
  is 
  more 
  

   or 
  less 
  darkly 
  coloured. 
  It 
  never 
  notices 
  any 
  of 
  our 
  white 
  

   Pierines. 
  

  

  I 
  have 
  stated 
  that 
  scent 
  does 
  not 
  appear 
  to 
  be 
  a 
  strong 
  

   factor 
  in 
  the 
  early 
  stages 
  of 
  courtship. 
  It 
  is 
  quite 
  otherwise 
  

   when 
  pairing 
  is 
  imminent 
  or 
  accomplished. 
  Mr. 
  Hamm 
  

   noticed 
  a 
  pair 
  of 
  euphrosyne, 
  in 
  coitu, 
  hidden 
  on 
  the 
  under- 
  

  

  