﻿356 
  ANNUAL, 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  the 
  period 
  of 
  reconstruction 
  than 
  would 
  a 
  soft-bodied 
  thing 
  like 
  

   the 
  propupa. 
  The 
  color 
  of 
  the 
  chrysalis 
  is 
  at 
  first 
  bright 
  green 
  on 
  

   the 
  foreparts, 
  yellowish 
  on 
  the 
  abdomen, 
  and 
  usually 
  more 
  or 
  less 
  

   brown 
  on 
  the 
  back. 
  But 
  it 
  soon 
  darkens 
  till 
  the 
  fore 
  parts 
  and 
  the 
  

   wings 
  are 
  purplish 
  black 
  and 
  the 
  abdomen 
  purplish 
  brown. 
  

  

  The 
  changes 
  that 
  have 
  taken 
  place 
  in 
  the 
  mouth 
  parts, 
  antenna?, 
  

   legs, 
  and 
  wings 
  since 
  the 
  propupal 
  period 
  are 
  shown 
  at 
  I 
  on 
  Figure 
  

   17. 
  The 
  legs 
  and 
  wings 
  are 
  folded 
  flat 
  against 
  the 
  body, 
  the 
  antennae 
  

   (Ant) 
  are 
  straightened 
  out 
  against 
  the 
  edges 
  of 
  the 
  wings, 
  the 
  max- 
  

   illae 
  (Mx) 
  are 
  longer 
  than 
  in 
  the 
  propupa 
  (H), 
  and 
  the 
  mouth 
  (Mth) 
  

   is 
  closed 
  to 
  a 
  narrow 
  slit. 
  

  

  From 
  now 
  on 
  the 
  external 
  form 
  of 
  the 
  pupa 
  will 
  not 
  change, 
  but 
  

   the 
  processes 
  of 
  transformation 
  will 
  go 
  on 
  rapidly 
  within 
  it 
  during 
  

   the 
  next 
  three 
  weeks. 
  Then 
  the 
  fully 
  formed 
  moth 
  will 
  discard 
  the 
  

   pupal 
  shell, 
  just 
  as 
  the 
  pupa 
  rejected 
  the 
  skin 
  of 
  the 
  caterpillar 
  after 
  

   the 
  latter 
  had 
  served 
  as 
  a 
  covering 
  during 
  its 
  formative 
  propupal 
  

   period. 
  

  

  We 
  have 
  seen 
  that 
  the 
  caterpillar's 
  business 
  is 
  to 
  eat. 
  Its 
  wormlike 
  

   form, 
  supposedly, 
  is 
  one 
  better 
  adapted 
  to 
  the 
  securing 
  of 
  food 
  than 
  

   the 
  moth 
  form. 
  Therefore, 
  the 
  young 
  moth 
  hatches 
  out 
  of 
  the 
  egg 
  

   as 
  a 
  caterpillar, 
  provided 
  with 
  external 
  organs, 
  alimentary 
  canal, 
  

   and 
  silk 
  glands 
  all 
  ready 
  for 
  its 
  work, 
  and 
  a 
  system 
  of 
  muscles 
  that 
  

   will 
  accomplish 
  all 
  its 
  necessary 
  movements. 
  But 
  these 
  parts 
  be- 
  

   come 
  suddenly 
  useless 
  when 
  the 
  insect 
  reaches 
  the 
  end 
  of 
  the 
  cater- 
  

   pillar 
  stage. 
  Consequently 
  they 
  must 
  be 
  discarded 
  or 
  made 
  over 
  

   into 
  the 
  corresponding 
  organs 
  of 
  the 
  moth 
  if 
  the 
  insect 
  is 
  to 
  complete 
  

   its 
  life 
  and 
  produce 
  another 
  generation. 
  The 
  necessity 
  for 
  this 
  

   change 
  is 
  the 
  reason 
  for 
  the 
  pupal 
  period. 
  The 
  departure 
  of 
  the 
  

   pupa 
  from 
  the 
  direct 
  road 
  from 
  the 
  propupa 
  to 
  the 
  adult 
  necessi- 
  

   tates 
  another 
  molt 
  and 
  establishes 
  the 
  pupa 
  as 
  a 
  separate 
  stage 
  in 
  the 
  

   insect's 
  growth, 
  though 
  it 
  is 
  really 
  but 
  the 
  fortnative 
  period 
  of 
  the 
  

   moth 
  and 
  is 
  to 
  be 
  regarded 
  as 
  a 
  part 
  of 
  the 
  adult 
  stage. 
  

  

  During 
  the 
  re-formation 
  it 
  is 
  necessary 
  that 
  continuity 
  be 
  pre- 
  

   served 
  in 
  most 
  of 
  the 
  parts, 
  else 
  the 
  animal 
  would 
  fall 
  to 
  pieces 
  

   somewhere 
  in 
  the 
  process. 
  Reconstruction, 
  therefore, 
  keeps 
  on 
  the 
  

   heels 
  of 
  disintegration, 
  and 
  in 
  all 
  the 
  tissues, 
  except 
  some 
  of 
  the 
  

   muscles, 
  the 
  newly 
  forming 
  parts 
  are 
  always 
  present 
  along 
  with 
  the 
  

   remains 
  of 
  the 
  old. 
  Hence, 
  while 
  the 
  external 
  form 
  of 
  an 
  organ 
  may 
  

   be 
  changing, 
  it 
  always 
  appears 
  to 
  be 
  intact. 
  It 
  is 
  only 
  by 
  a 
  micro- 
  

   scopic 
  examination 
  of 
  tissues 
  prepared 
  for 
  a 
  study 
  of 
  their 
  cells 
  

   that 
  it 
  is 
  possible 
  to 
  see 
  what 
  is 
  really 
  taking 
  place 
  in 
  them. 
  The 
  de- 
  

   tails 
  have 
  been 
  described 
  by 
  many 
  investigators, 
  who 
  agree 
  pretty 
  

   well 
  on 
  the 
  following 
  points. 
  

  

  