﻿EMBRYOLOGY 
  OF 
  ORTHOPTEROUS 
  INSECTS. 
  271 
  

  

  except 
  in 
  a 
  very 
  rudimentary 
  way, 
  as 
  perhaps 
  masses 
  of 
  internal 
  in- 
  

   different 
  cells 
  (imaginal 
  disks), 
  to 
  the 
  larva, 
  being 
  the 
  rather 
  destined 
  

   to 
  develop 
  late 
  in 
  larval 
  and 
  in 
  pupal 
  life. 
  Thus 
  the 
  development 
  of 
  the 
  

   wings 
  and 
  of 
  the 
  generative 
  organs 
  would 
  go 
  hand 
  in 
  hand, 
  and 
  become 
  

   organs 
  of 
  adult 
  life. 
  

  

  It 
  is 
  not 
  improbable 
  that 
  the 
  metamorphoses 
  in 
  insects 
  were 
  primarily 
  

   due 
  to 
  the 
  acquisition 
  of 
  wings, 
  and 
  that 
  the 
  latter 
  were 
  likewise 
  pri- 
  

   marily 
  due 
  to 
  the 
  ripening 
  of 
  the 
  sexual 
  organs. 
  We 
  see 
  that 
  in 
  Or- 
  

   thoptera, 
  Blatta 
  especially, 
  the 
  larvae 
  only 
  differ 
  from 
  the 
  adult 
  in 
  

   wanting 
  wings 
  and 
  in 
  having 
  undeveloped 
  genital 
  organs. 
  Metamor- 
  

   phosis, 
  then, 
  in 
  insects, 
  is 
  correlated 
  most 
  intimat<?ly 
  with 
  the 
  presence 
  

   or 
  absence 
  of 
  wings. 
  Moreover, 
  the 
  differentiation 
  of 
  the 
  meso- 
  and 
  

   metanotum 
  is 
  closely 
  dependent 
  on 
  the 
  presence 
  of 
  wings. 
  Wherever 
  

   the 
  wings 
  are 
  wanting 
  the 
  scutum, 
  scutellum, 
  &c., 
  are 
  not 
  differentiated. 
  

  

  The 
  next 
  step 
  above 
  the 
  Orthoptera 
  are 
  the 
  Pseudoneuroptera, 
  such 
  

   as 
  Perlidse, 
  Psocidse, 
  and 
  Termitidsej 
  and 
  finally 
  the 
  Odonata 
  and 
  Ephe- 
  

   meridae. 
  In 
  all 
  these 
  forms 
  the 
  metamorphosis 
  is 
  incomplete, 
  the 
  chief 
  

   difference 
  between 
  the 
  larva 
  and 
  adult 
  being 
  the 
  presence 
  of 
  wings 
  and 
  

   of 
  ripe 
  ovaries 
  and 
  testes. 
  So 
  it 
  is 
  with 
  the 
  Hemiptera. 
  

  

  When 
  we 
  ascend 
  to 
  the 
  true 
  Neuroptera 
  we 
  see 
  a 
  greater 
  difference 
  

   between 
  the 
  larva 
  and 
  the 
  imago, 
  and 
  a 
  third, 
  i. 
  e., 
  quiescent 
  pupal 
  

   stage. 
  Here 
  adaptive 
  characters 
  come 
  in. 
  The 
  caddis 
  worms, 
  post>i- 
  

   bly 
  derived 
  from 
  Sialid 
  forms, 
  and 
  constructing 
  tubular 
  cases, 
  acquired 
  

   cylindrical 
  instead 
  of 
  flattened 
  bodies; 
  rapidly 
  feeding 
  up, 
  they, 
  by 
  

   some 
  means, 
  acquired 
  the 
  habit 
  of 
  resting 
  in 
  closed 
  cases, 
  and 
  dur- 
  

   ing 
  this 
  quiescent 
  period 
  the 
  wings 
  and 
  genital 
  organs 
  would 
  become 
  

   prematurely 
  developed, 
  until, 
  as 
  soon 
  as 
  the 
  pupal 
  sleep 
  was 
  ended, 
  the 
  

   sexual 
  powers 
  being 
  ripe, 
  the 
  wings 
  would 
  suddenly 
  attain 
  their 
  full 
  

   development, 
  and 
  the 
  insect, 
  the 
  caddis 
  fly, 
  for 
  example, 
  would 
  both 
  

   sexually 
  and 
  as 
  regards 
  powers 
  of 
  flight 
  become 
  highly 
  active. 
  

  

  Given 
  a 
  few 
  cases 
  of 
  complete 
  metamorphosis 
  in 
  the 
  Keuroptera, 
  es- 
  

   pecially 
  Phryganeidae 
  and 
  Sialidae, 
  we 
  can 
  explain 
  the 
  origin 
  of 
  a 
  meta- 
  

   morphosis 
  in 
  the 
  higher 
  orders. 
  As 
  the 
  Coleoptera 
  have 
  probably 
  de- 
  

   scended 
  from 
  lost 
  forms 
  resembling 
  thei 
  Sialid 
  Neuroptera, 
  and 
  the 
  

   Lei)idoptera 
  and 
  Trichoptera 
  from 
  a 
  common 
  stock, 
  the 
  Diptera 
  and 
  

   Hymenoptera 
  being 
  also 
  probable 
  offshoots 
  from 
  the 
  primitive 
  Lepi- 
  

   dopterous 
  stock, 
  it 
  is 
  easy 
  to 
  see 
  how 
  the 
  majority 
  of 
  insects 
  which 
  be- 
  

   long 
  to 
  the 
  metabolous 
  orders 
  should 
  all 
  have 
  a 
  complete 
  metamorphosis, 
  

   this 
  being 
  secondary 
  and 
  adaptive 
  in 
  its 
  nature. 
  

  

  THE 
  EMBRYOLOGICAL 
  DEVELOPMENT 
  OF 
  ORTHOPTEROUS 
  INSECTS. 
  

  

  In 
  order 
  to 
  elucidate 
  the 
  earliest 
  steps 
  in 
  the 
  development 
  of 
  the 
  

   locust, 
  so 
  as 
  to 
  complete 
  far 
  as 
  possible 
  our 
  knowledge 
  of 
  the 
  nat- 
  

   ural 
  history 
  of 
  the 
  locust, 
  as 
  well 
  as 
  to 
  examine 
  the 
  embryology 
  of 
  a 
  

   typical 
  orthopterous 
  insect, 
  the 
  following 
  researches 
  were 
  under- 
  

   taken. 
  The 
  results 
  are 
  imperfect 
  and 
  fragmentary, 
  as 
  it 
  was 
  not 
  easy 
  

  

  