﻿l?ROCEEt)INGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  

  

  The 
  record 
  of 
  the 
  experiment 
  is 
  as 
  follows 
  : 
  — 
  

  

  281 
  

  

  Distance 
  

   from 
  fly. 
  

  

  FhjA- 
  

   V 
  

  

  4' 
  

  

  5' 
  . 
  

  

  7' 
  . 
  

  

  n' 
  . 
  

  

  FUjB— 
  

  

  6' 
  . 
  

  

  9' 
  . 
  

  

  14' 
  . 
  

  

  17' 
  . 
  

  

  Object. 
  

  

  Paper 
  4" 
  sq. 
  . 
  . 
  

   Fan 
  12" 
  diara. 
  

   Fawn 
  hat 
  15" 
  diam. 
  

  

  Paper 
  . 
  . 
  . 
  

  

  Fan 
  

  

  Fan 
  

   Body 
  

  

  Minimum 
  shift 
  

   required. 
  

  

  4—6*. 
  

  

  4" 
  

  

  6—10* 
  

  

  6" 
  (once). 
  

   Generally 
  8—10" 
  

   10—12" 
  

  

  12* 
  once 
  ; 
  generally 
  

   15—18". 
  

  

  less 
  than 
  2i' 
  . 
  

  

  2i' 
  

   4' 
  

  

  1' 
  

  

  3' 
  

  

  8' 
  

  

  More 
  than 
  13' 
  

  

  E/EMABKS. 
  

  

  Turning 
  the 
  fan 
  from 
  

   edgeways 
  to 
  broadside 
  

   on 
  was 
  always 
  effective. 
  

  

  Turning 
  was 
  once 
  effect. 
  

  

  tive. 
  

  

  I 
  moved 
  by 
  stepping 
  side- 
  

   ways 
  as 
  abruptly 
  as 
  

   possible 
  ; 
  in 
  the 
  longer 
  

   distances 
  by 
  springing 
  

   quickly 
  from 
  one 
  point 
  

   to 
  another. 
  

  

  The 
  hand 
  moved 
  quickly 
  

   through 
  r 
  produced 
  no 
  

   effect. 
  

  

  Waving 
  the 
  arms 
  was 
  in- 
  

   effective 
  ; 
  bandishing 
  a 
  

   short-handled 
  net 
  in- 
  

   effective. 
  

  

  Rapidly 
  leaping 
  and 
  run- 
  

   ning 
  across 
  the 
  13' 
  was 
  

   ineffective. 
  Trees 
  pre- 
  

   vented 
  a 
  longer 
  run. 
  

  

  The 
  accompanying 
  diagram 
  gives 
  the 
  various 
  distances 
  plotted. 
  

  

  An 
  experiment 
  conducted 
  in 
  this 
  rough-and-ready 
  way 
  cannot 
  be 
  

   expected 
  to 
  give 
  very 
  accurate 
  numerical 
  data 
  regarding 
  the 
  power 
  of 
  

   vision 
  in 
  the 
  flies, 
  but 
  in 
  view 
  of 
  the 
  degree 
  of 
  concordance 
  of 
  the 
  results 
  

   and 
  the 
  care 
  with 
  which 
  they 
  were 
  obtained 
  we 
  may 
  take 
  it 
  that 
  the 
  

   general 
  form 
  of 
  the 
  curve 
  is 
  in 
  all 
  probability 
  fairly 
  correct. 
  

  

  