﻿the 
  markings 
  and 
  colouring 
  of 
  Lejndoptera. 
  169 
  

  

  is 
  the 
  much 
  lower 
  "cooling" 
  temperature 
  (of 
  43°), 
  but 
  that 
  

   exposing 
  the 
  pupa 
  during 
  its 
  last 
  two 
  or 
  three 
  days 
  to 
  a 
  forcing 
  

   temperature 
  may 
  be 
  enough 
  to 
  affect 
  the 
  colouring 
  in 
  the 
  opposite 
  

   direction. 
  

  

  Period 
  of 
  pufal 
  development 
  lohen 
  temferature 
  operates 
  on 
  

   colour. 
  — 
  The 
  next 
  experiments 
  were 
  made 
  with 
  the 
  object 
  of 
  

   endeavom'ing 
  to 
  define 
  still 
  more 
  closely 
  the 
  period 
  of 
  pupal 
  

   development 
  during 
  which 
  the 
  temperature 
  has 
  to 
  be 
  applied 
  in 
  

   order 
  to 
  develop 
  its 
  effects 
  on 
  colouring. 
  For 
  this 
  purpose 
  the 
  

   second 
  " 
  red" 
  brood, 
  distinguished 
  as 
  " 
  red 
  a," 
  which 
  had 
  been 
  at 
  

   the 
  icing 
  temperature 
  for 
  about 
  fourteen 
  weeks, 
  was 
  taken. 
  Eight 
  

   moths, 
  the 
  pupae 
  of 
  which 
  had 
  been 
  forced 
  from 
  the 
  time 
  they 
  

   hardened, 
  are 
  scarcely 
  to 
  be 
  distinguished 
  from 
  the 
  "red 
  c" 
  

   similarly 
  treated, 
  being 
  of 
  the 
  same 
  light 
  warm 
  tint, 
  and 
  with 
  the 
  

   usual 
  summer 
  markings. 
  Of 
  those 
  not 
  so 
  forced 
  I 
  had 
  about 
  

   seventy 
  pupae. 
  This 
  brood, 
  however, 
  was 
  not 
  so 
  healthy 
  and 
  

   vigorous 
  as 
  the 
  "red 
  c's". 
  Whether 
  from 
  this 
  or 
  some 
  other 
  

   cause, 
  the 
  differences 
  in 
  colom-ing 
  caused 
  by 
  the 
  treatment 
  are 
  not 
  

   so 
  marked 
  as 
  in 
  " 
  red 
  c." 
  

  

  It 
  should 
  be 
  premised 
  that 
  all 
  the 
  experiments 
  on 
  illustraria 
  

   under 
  heads 
  (d) 
  and 
  (e) 
  subsequently 
  detailed 
  were 
  tried 
  with 
  sum- 
  

   mer 
  pupae 
  which 
  had 
  been 
  iced 
  about 
  fourteen 
  weeks, 
  a 
  treatment 
  

   which, 
  as 
  already 
  shown, 
  appears 
  to 
  affect 
  the 
  markings 
  rather 
  than 
  

   the 
  colouring. 
  

  

  Fourteen 
  male 
  and 
  fourteen 
  female 
  pupas 
  were, 
  on 
  the 
  25th 
  

   Sept., 
  taken 
  from 
  the 
  ice 
  and 
  divided 
  into 
  two 
  parts, 
  and 
  were 
  

   then 
  treated 
  as 
  follows 
  : 
  — 
  

  

  (d) 
  Forcing 
  for 
  different 
  periods 
  succeeded 
  by 
  a 
  moderately 
  

   low 
  tetnperature. 
  — 
  With 
  the 
  first 
  division, 
  consisting 
  of 
  six 
  males 
  

   and 
  six 
  females, 
  the 
  experiment 
  was 
  tried 
  of 
  first 
  forcing 
  and 
  then 
  

   from 
  day 
  to 
  day 
  removing 
  into 
  the 
  open 
  air, 
  which 
  at 
  8 
  a.m. 
  

   averaged 
  about 
  56°. 
  From 
  the 
  Table 
  (I.) 
  appended 
  it 
  will 
  be 
  seen 
  

   that 
  they 
  were, 
  when 
  taken 
  from 
  the 
  ice 
  on 
  the 
  25th, 
  ready 
  to 
  

   emerge 
  in 
  about 
  five 
  days 
  of 
  a 
  forcing 
  temperature. 
  This 
  indicates 
  

   that 
  the 
  pupal 
  period, 
  measured 
  by 
  the 
  progress 
  made, 
  was 
  then 
  

   not 
  quite 
  half 
  over, 
  for 
  I 
  have 
  found 
  that 
  the 
  summer 
  pupa 
  

   exposed 
  to 
  a 
  forcing 
  temperature 
  usually 
  emerges 
  in 
  from 
  eight 
  to 
  

   ten 
  days. 
  The 
  results 
  were 
  as 
  follows 
  :—Nos. 
  1 
  g' 
  and 
  2 
  ^, 
  and 
  

   Nos. 
  1 
  5 
  and 
  2 
  J 
  , 
  which 
  had 
  been 
  deprived 
  of 
  a 
  forcing 
  tem- 
  

   perature 
  during 
  two 
  or 
  three 
  out 
  of 
  their 
  last 
  five 
  days, 
  are 
  

   decidedly 
  darker 
  than 
  the 
  others 
  ; 
  of 
  the 
  remainder, 
  No. 
  3 
  <y 
  , 
  

   which 
  had 
  been 
  deprived 
  of 
  but 
  one 
  day's 
  forcing, 
  is 
  lighter, 
  

   No. 
  5 
  (? 
  was 
  accidentally 
  lost, 
  and 
  No. 
  6 
  ^ 
  , 
  which 
  was 
  forced 
  the 
  

   whole 
  of 
  the 
  five 
  days, 
  is 
  almost 
  of 
  the 
  summer 
  colouring 
  of 
  the 
  

  

  