﻿156 
  Mr. 
  F. 
  Merrifield 
  uii 
  conspicuous 
  effects 
  on 
  

  

  firmed 
  my 
  suspicion. 
  I 
  obtained 
  more 
  striking 
  results 
  

   than 
  before, 
  and 
  the 
  fact 
  was 
  brought 
  out 
  that 
  the 
  change 
  

   of 
  markings 
  due 
  to 
  temperature 
  was 
  caused 
  by 
  tem- 
  

   perature 
  conditions 
  so 
  different 
  from 
  those 
  which 
  caused 
  

   colouring, 
  or 
  darkness, 
  that 
  it 
  became 
  possible 
  artificially 
  

   to 
  produce 
  either 
  effect 
  with 
  little 
  or 
  no 
  admixture 
  of 
  the 
  

   other 
  ; 
  so, 
  for 
  example, 
  as 
  to 
  get 
  from 
  the 
  same 
  brood 
  

   of 
  an 
  insect 
  which 
  is 
  subject 
  to 
  seasonal 
  dimorphism 
  

   what 
  may 
  be 
  termed, 
  speaking 
  generally, 
  four 
  distinct 
  

   temperature 
  varieties, 
  viz., 
  (1) 
  summer 
  markings 
  with 
  

   summer 
  colouring, 
  (2) 
  summer 
  markings 
  with 
  an 
  approach 
  

   towards 
  spring 
  colouring, 
  (3) 
  spring 
  markings 
  with 
  sum- 
  

   mer 
  colouring, 
  (4) 
  spring 
  markings 
  with 
  spring 
  colouring. 
  

   It 
  will 
  be 
  seen 
  that 
  all 
  these 
  results 
  have 
  been 
  more 
  or 
  

   less 
  fully 
  obtained 
  ; 
  three 
  of 
  them 
  from 
  a 
  single 
  brood, 
  and 
  

   the 
  fourth 
  from 
  another 
  precisely 
  similar 
  brood, 
  might 
  

   certainly 
  have 
  been 
  obtained 
  from 
  the 
  first 
  brood 
  had 
  a 
  

   portion 
  of 
  it 
  been 
  subjected 
  to 
  the 
  appropriate 
  treatment. 
  

  

  When 
  I 
  use 
  the 
  term 
  spring 
  and 
  summer 
  markings 
  

   or 
  colouring 
  (in 
  which 
  last 
  word 
  I 
  include 
  lightness 
  or 
  

   darkness 
  of 
  hue) 
  I 
  am 
  only 
  speaking 
  generally. 
  I 
  have 
  

   not 
  yet, 
  I 
  think, 
  met 
  with 
  a 
  case 
  where 
  the 
  summer 
  

   moth 
  has 
  been 
  made 
  to 
  assume 
  the 
  exact 
  colouring 
  of 
  

   the 
  spring 
  insect, 
  but, 
  as 
  regards 
  markings, 
  I 
  think 
  the 
  

   resemblance 
  is 
  complete, 
  or 
  nearly 
  so. 
  

  

  For 
  purposes 
  of 
  description, 
  it 
  has 
  been 
  found 
  neces- 
  

   sary 
  to 
  divide 
  the 
  pupal 
  period 
  into 
  four 
  stages, 
  the 
  

   duration 
  of 
  each 
  of 
  which 
  greatly 
  depends 
  on 
  the 
  tem- 
  

   perature, 
  viz. 
  ; 
  — 
  (1) 
  the 
  soft 
  condition, 
  which, 
  at 
  ordinary 
  

   summer 
  temperature, 
  continues 
  about 
  twenty-four 
  hours 
  

   or 
  less 
  ; 
  (2) 
  the 
  central 
  inactive 
  condition, 
  which 
  may 
  

   last 
  for 
  a 
  few 
  days 
  onlj^ 
  or 
  for 
  many 
  months 
  ; 
  (3) 
  what 
  

   I 
  would 
  term 
  the 
  penultimate 
  stage, 
  being 
  that 
  separating 
  

   the 
  inactive 
  period 
  from 
  (4) 
  the 
  last 
  stage, 
  commencing 
  

   when 
  the 
  colours 
  of 
  the 
  pupal 
  insect 
  begin 
  to 
  show. 
  Each 
  

   of 
  the 
  stages 
  (3) 
  and 
  (4), 
  at 
  the 
  summer 
  temperature, 
  

   seems 
  to 
  last, 
  in 
  the 
  two 
  species 
  experimented 
  on, 
  two 
  

   or 
  three 
  days, 
  but 
  at 
  a 
  lower 
  temperature 
  can 
  extend 
  

   over 
  several 
  weeks. 
  

  

  The 
  icing 
  temperature 
  may 
  be 
  taken 
  as 
  a 
  steady 
  

   33"Fahr. 
  (subject 
  to 
  the 
  qualification 
  that 
  from 
  about 
  

   the 
  beginning 
  of 
  July 
  of 
  this 
  year 
  to 
  the 
  10th 
  August, 
  

   during 
  which 
  the 
  pupae, 
  instead 
  of 
  being 
  in 
  an 
  ice-box, 
  

   were 
  placed 
  under 
  the 
  bottom 
  of 
  the 
  ice-holder 
  in 
  the 
  

  

  