﻿272 
  EEPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  to 
  obtain 
  full 
  series 
  of 
  eggs 
  laid 
  from 
  the 
  time 
  of 
  oviposition 
  to 
  that 
  of 
  

   hatching. 
  Our 
  examination 
  of 
  eggs 
  confirms 
  what 
  Mr. 
  Eiley 
  had 
  pre- 
  

   viously 
  stated, 
  that 
  the 
  young 
  develop 
  in 
  the 
  autumn, 
  though 
  most 
  of 
  

   them 
  delay 
  hatching 
  until 
  the 
  spring. 
  From 
  our 
  observations, 
  it 
  ap- 
  

   jjears 
  that 
  the 
  embryo 
  locust 
  begins 
  to 
  develop 
  as 
  soon 
  as 
  the 
  eggs 
  are 
  

   impregnated, 
  this 
  act 
  taking 
  place, 
  as 
  well 
  known, 
  during 
  oviposition 
  

   in 
  the 
  soil. 
  The 
  embryo, 
  probably, 
  passes 
  through 
  the 
  earlier 
  and 
  

   indeed 
  nearly 
  all 
  the 
  embryonic 
  stages 
  before 
  winter 
  sets 
  in; 
  the 
  em- 
  

   bryo 
  being 
  nearly 
  or 
  quite 
  ready 
  to 
  hatch 
  probably 
  within 
  a 
  month 
  

   after 
  the 
  eggs 
  are 
  laid. 
  It 
  is 
  therefore 
  not 
  surprising 
  that 
  a 
  few 
  un- 
  

   usually 
  warm 
  days 
  in 
  l^ovember 
  or 
  early 
  December 
  may 
  cause 
  an 
  ac- 
  

   celeration 
  in 
  the 
  development 
  of 
  the 
  embryo, 
  and 
  that 
  young 
  locusts 
  

   should 
  then 
  hatch, 
  while 
  the 
  majority 
  of 
  young 
  do 
  not 
  hatch 
  until 
  the 
  

   following 
  spring. 
  

  

  The 
  only 
  observations, 
  so 
  far 
  as 
  we 
  are 
  aware, 
  on 
  the 
  embryology 
  of 
  

   any 
  orthopterous 
  insect, 
  are 
  those 
  of 
  Dr. 
  Anton 
  Dohrn, 
  on 
  some 
  stages 
  in 
  

   the 
  development 
  of 
  the 
  European 
  mole 
  cricket, 
  published 
  in 
  8iebold 
  and 
  

   Kolliker's 
  Zeitschrift 
  flir 
  wissenschaltliche 
  Zoologie, 
  xxvi, 
  1876 
  (with 
  

   no 
  illustrations). 
  

  

  In 
  this 
  paper 
  Dr. 
  Dohrn 
  showed 
  that 
  in 
  Gry 
  Hot 
  alpa, 
  or 
  the 
  mole 
  cricket, 
  

   the 
  primitive 
  streak 
  incloses 
  the 
  yolk. 
  On 
  the 
  sides 
  and 
  at 
  each 
  end 
  tlie 
  

   primitive 
  band 
  is 
  continued 
  into 
  a 
  membrane, 
  which 
  passes 
  around 
  it 
  

   and 
  envelops 
  the 
  embryo; 
  this 
  is 
  the 
  amnion. 
  The 
  ser6us 
  membrane 
  is 
  

   likewise 
  present 
  and 
  seems 
  to 
  be 
  united 
  with 
  the 
  amnion 
  into 
  one 
  mem- 
  

   brane. 
  

  

  The 
  position 
  of 
  the 
  embryo 
  at 
  this 
  time 
  is 
  such 
  that 
  the 
  head 
  begins 
  

   at 
  the 
  middle 
  point 
  of 
  the 
  back 
  part 
  of 
  the 
  egg, 
  the 
  mouth 
  appendages 
  

   on 
  the 
  anterior 
  pole, 
  the 
  ventral 
  segments 
  on 
  the 
  ventral 
  side, 
  and 
  the 
  

   anus 
  now 
  is 
  situated 
  on 
  the 
  hinder 
  pole 
  of 
  the 
  egg. 
  

  

  In 
  this 
  position 
  and 
  when 
  the 
  appendages 
  have 
  already 
  reached 
  a 
  

   considerable 
  size, 
  Dohrn 
  noticed 
  the 
  first 
  appearance 
  of 
  motion 
  in 
  the 
  

   embryo. 
  This 
  consists 
  of 
  slight 
  contractions 
  of 
  a 
  thin 
  membrane. 
  

  

  Dr. 
  Dohrn 
  observed 
  how 
  both 
  leaves 
  of 
  the 
  embryonal 
  skins 
  are 
  

   united 
  before 
  the 
  head, 
  how 
  their 
  cells 
  undergo 
  a 
  fatty 
  degeneration, 
  

   how 
  the 
  skin 
  becomes 
  thinner 
  and 
  more 
  transparent, 
  and 
  how 
  in 
  other 
  

   parts 
  of 
  the 
  membrane 
  a 
  kind 
  of 
  streak-formation 
  sets 
  in, 
  while 
  the 
  cells 
  

   seem 
  arranged 
  in 
  rows. 
  At 
  the 
  same 
  time 
  the 
  whole 
  membrane, 
  which 
  

   until 
  now 
  has 
  laid 
  directl}^ 
  against 
  theinner 
  egg-lnembrane, 
  is 
  seen 
  to 
  con. 
  

   tinuously 
  contract, 
  so 
  that, 
  finally, 
  the 
  entire 
  interspace 
  which 
  separated 
  

   it 
  from 
  the 
  embryo, 
  especially 
  on 
  the 
  fore 
  body, 
  disappeared, 
  while 
  the 
  

   apjjendages 
  which 
  extended 
  out 
  free 
  into 
  this 
  space 
  were, 
  by 
  the 
  pres- 
  

   sure 
  of 
  the 
  embryonal 
  skins, 
  pressed 
  into 
  the 
  primitive 
  band, 
  so 
  that 
  tbey 
  

   were 
  not 
  to 
  be 
  seen. 
  Shortly 
  the 
  whole 
  embryo 
  lay 
  like 
  a 
  ball 
  within 
  

   the 
  egg-skins. 
  

  

  The 
  digestive 
  canal 
  of 
  insect-embrj^os 
  consists 
  of 
  three 
  portions: 
  fore, 
  

   middle, 
  and 
  hind 
  gut. 
  The 
  formation 
  of 
  these 
  three 
  parts 
  does 
  not 
  take 
  

  

  