﻿( 
  420 
  ) 
  

  

  XV. 
  On 
  the 
  Histology 
  of 
  the 
  Scent-organs 
  in 
  the 
  Genus 
  

   Hvdroptila, 
  Dal. 
  Bv 
  H. 
  Eltringham, 
  M.A., 
  

  

  D'.Sc., 
  F.Z.S. 
  

  

  [Read 
  November 
  5th, 
  1919.] 
  

  

  Plate 
  XXII. 
  

  

  My 
  friend 
  Mr. 
  Martin 
  E. 
  Mosely 
  has 
  made 
  a 
  discovery 
  of 
  

   the 
  first 
  importance, 
  which 
  should 
  prove 
  of 
  the 
  greatest 
  

   interest 
  to 
  entomologists. 
  In 
  a 
  paper 
  read 
  before 
  this 
  

   Society 
  on 
  October 
  15th 
  (p. 
  393), 
  he 
  described 
  the 
  external 
  

   features 
  of 
  certain 
  organs 
  in 
  the 
  heads 
  of 
  various 
  species 
  

   of 
  the 
  Trichopterid 
  genus 
  Hgdroptila. 
  

  

  Mistrusting 
  his 
  own 
  skill 
  as 
  a 
  microtomist 
  with 
  a 
  lack 
  

   of 
  faith 
  which, 
  judging 
  from 
  some 
  of 
  his 
  excellent 
  prepara- 
  

   tions, 
  I 
  regard 
  as 
  unfounded, 
  he 
  has 
  done 
  me 
  the 
  honour 
  

   to 
  hand 
  over 
  to 
  me 
  a 
  supply 
  of 
  material 
  for 
  the 
  investiga- 
  

   tion 
  of 
  the 
  minute 
  structure 
  of 
  these 
  organs. 
  Just 
  as 
  

   Science 
  generally 
  is 
  indebted 
  to 
  him 
  for 
  his 
  discovery, 
  I 
  

   am 
  personally 
  under 
  an 
  obligation 
  to 
  him 
  for 
  enabUng 
  

   me 
  to 
  carry 
  out 
  an 
  examination 
  of 
  unusual 
  interest 
  and 
  

   fascination. 
  

  

  Some 
  time 
  ago 
  I 
  described 
  and 
  illustrated 
  the 
  scent- 
  

   organs 
  in 
  certain 
  male 
  Danaine 
  butterflies 
  (Trans. 
  Ent. 
  

   Soc, 
  1913, 
  p. 
  399; 
  1914, 
  p. 
  152). 
  

  

  It 
  will 
  be 
  remembered 
  that 
  these 
  included 
  certain 
  

   eversible 
  brushes 
  located 
  in 
  the 
  extremity 
  of 
  the 
  abdomen. 
  

   These 
  brushes 
  were 
  formed 
  of 
  hairs 
  of 
  varying 
  structure 
  

   set 
  on 
  the 
  inner 
  surface 
  of 
  an 
  eversible 
  membranous 
  bag, 
  

   so 
  that 
  when 
  the 
  latter 
  was 
  everted, 
  doubtless 
  by 
  fluid 
  

   pressure, 
  the 
  hairs 
  projected 
  from 
  its 
  now 
  outer 
  surface. 
  

   In 
  some 
  cases 
  the 
  scent 
  material 
  was 
  obtained 
  from 
  glands 
  

   in 
  the 
  wings, 
  whilst 
  in 
  others 
  the 
  brushes 
  themselves 
  

   exhibited 
  a 
  glandular 
  structure. 
  

  

  We 
  know 
  from 
  the 
  work 
  of 
  Dr. 
  F. 
  A. 
  Dixey 
  and 
  others 
  

   that 
  certain 
  special 
  scales 
  on 
  the 
  wings 
  of 
  butterflies 
  act 
  

   as 
  scent-organs. 
  In 
  all 
  these 
  cases 
  the 
  scent-scales, 
  brushes, 
  

   glands, 
  etc., 
  are 
  of 
  comparatively 
  considerable 
  size, 
  and 
  

   occur 
  on 
  insects 
  which, 
  even 
  in 
  the 
  case 
  of 
  Lycaenids, 
  are 
  

   large 
  compared 
  with 
  Hydroptila. 
  These 
  httle 
  creatures 
  

  

  TRANS. 
  ENT. 
  SOC. 
  LOND. 
  1919. 
  — 
  PARTS 
  III, 
  IV. 
  (dEC.) 
  

  

  