﻿360 
  

  

  ANNUAL, 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  Ant- 
  

  

  (Lb) 
  of 
  the 
  moth 
  is 
  reduced 
  almost 
  to 
  nothing, 
  but 
  its 
  palpi 
  (LbPlp) 
  

   are 
  long 
  and 
  three- 
  jointed. 
  When 
  covered 
  with 
  their 
  scales 
  these 
  

   palpi 
  form 
  the 
  two 
  furry 
  brushes 
  that 
  project 
  in 
  front 
  of 
  the 
  face. 
  

  

  In 
  most 
  moths 
  the 
  two 
  maxillae 
  are 
  drawn 
  out 
  into 
  a 
  pair 
  of 
  long 
  

   straps, 
  the 
  grooved 
  inner 
  faces 
  of 
  which 
  are 
  united 
  to 
  form 
  a 
  tube 
  

   or 
  proboscis 
  through 
  which 
  the 
  moth 
  sucks 
  up 
  nectar 
  from 
  flowers 
  

   and 
  drinks 
  water. 
  In 
  some 
  species, 
  however, 
  such 
  as 
  the 
  fall 
  web- 
  

   worm 
  moth, 
  the 
  proboscis 
  is 
  short 
  and 
  perhaps 
  almost 
  useless 
  (see 
  

   p. 
  411 
  of 
  Smithsonian 
  Report 
  for 
  1921). 
  In 
  the 
  moth 
  of 
  the 
  tent 
  

   caterpillar 
  the 
  rnaxillae 
  are 
  so 
  small 
  that 
  they 
  do 
  not 
  form 
  any 
  pro- 
  

   boscis 
  at 
  all. 
  It 
  is 
  interesting 
  to 
  note 
  that 
  the 
  maxillae 
  of 
  the 
  tent 
  

   caterpillar 
  reach 
  their 
  greatest 
  length 
  in 
  the 
  pupa 
  (fig. 
  17, 
  I), 
  as 
  if 
  

  

  nature 
  had 
  intended 
  the 
  moth 
  to 
  have 
  

   a 
  proboscis, 
  but 
  changed 
  her 
  mind 
  

   and 
  had 
  the 
  maxillae 
  grow 
  backward 
  

   again 
  in 
  the 
  pupal 
  stage. 
  When 
  

   things 
  like 
  this 
  take 
  place 
  in 
  the 
  

   development 
  of 
  an 
  animal 
  zoologists 
  

   interpret 
  it 
  as 
  meaning 
  that 
  the 
  final 
  

   form 
  of 
  the 
  organ 
  has 
  been 
  acquired 
  

   recently, 
  referring, 
  of 
  course, 
  to 
  the 
  

   past 
  few 
  million 
  years. 
  

  

  Since 
  the 
  moth 
  eats 
  nothing 
  and 
  

   probably 
  drinks 
  nothing, 
  it 
  has 
  little 
  

   use 
  for 
  an 
  alimentary 
  canal. 
  But 
  im- 
  

   portant 
  organs, 
  though 
  useless, 
  are 
  

   seldom 
  obliterated. 
  Consequently 
  the 
  

   tent 
  caterpillar 
  moth 
  has 
  a 
  threadlike 
  

   tube 
  extending 
  backward 
  from 
  its 
  

   mouth 
  which 
  preserves 
  the 
  tradition 
  of 
  a 
  stomach, 
  an 
  organ 
  which 
  

   its 
  ancestors 
  once 
  possessed. 
  The 
  intestine 
  is 
  better 
  developed, 
  since 
  

   it 
  must 
  still 
  function 
  as 
  the 
  outlet 
  for 
  the 
  Malpighian 
  tubules. 
  The 
  

   secretion 
  of 
  these 
  tubes 
  during 
  the 
  pupal 
  period 
  consists 
  of 
  minute 
  

   spherical 
  crystals. 
  They 
  accumulate 
  in 
  the 
  rear 
  part 
  of 
  the 
  intestine 
  

   as 
  an 
  orange-colored 
  mass 
  which 
  is 
  discharged 
  as 
  soon 
  as 
  the 
  moth 
  

   leaves 
  the 
  cocoon. 
  

  

  Most 
  of 
  the 
  male 
  moths 
  emerge 
  from 
  the 
  cocoons 
  several 
  days 
  in 
  

   advance 
  of 
  the 
  females. 
  At 
  this 
  time 
  their 
  bodies 
  contain 
  an 
  abund- 
  

   ance 
  of 
  fat 
  tissue 
  (fig. 
  16, 
  B), 
  the 
  cells 
  of 
  which 
  are 
  filled 
  with 
  drop- 
  

   lets 
  of 
  fatty 
  oil, 
  as 
  shown 
  by 
  their 
  staining 
  deeply 
  with 
  osmic 
  acid 
  

   and 
  Soudan 
  III. 
  But 
  the 
  internal 
  reproductive 
  organs 
  of 
  the 
  male 
  

   are 
  not 
  yet 
  fully 
  developed 
  and 
  probably 
  do 
  not 
  become 
  functional 
  

   till 
  about 
  the 
  time 
  the 
  females 
  are 
  out 
  of 
  their 
  cocoons. 
  

  

  Mth 
  

  

  Fig. 
  19. 
  — 
  Head 
  of 
  the 
  inoth, 
  facial 
  

   view, 
  with 
  scales 
  removed 
  and 
  an- 
  

   tennae 
  cut 
  off 
  near 
  bases. 
  Ant, 
  

   antenna 
  ; 
  E, 
  eye 
  ; 
  Lb, 
  labium 
  ; 
  

   LbPlp, 
  labial 
  palpus 
  ; 
  Lm, 
  lagrum 
  ; 
  

   Mth, 
  mouth 
  ; 
  Mx, 
  maxilla. 
  

  

  