﻿STRUCTURE 
  OF 
  THE 
  OVARY. 
  199 
  

  

  PhthiriuS) 
  three 
  cords 
  spring 
  from 
  each 
  ovarian 
  tube, 
  instead 
  of 
  one 
  as 
  

   in 
  most 
  insects. 
  Leydig 
  280 
  considers 
  this 
  cord 
  to 
  be 
  hollow, 
  while 
  most 
  

   other 
  authors 
  describe 
  it 
  as 
  solid 
  in 
  the 
  insects 
  they 
  have 
  examined. 
  

   Xeither 
  in 
  the 
  locust 
  or 
  the 
  cricket 
  have 
  I 
  seen 
  any 
  trace 
  of 
  an 
  interior 
  

   cavity. 
  The 
  cord 
  is 
  covered 
  by 
  an 
  external 
  membrane, 
  very 
  thin, 
  and 
  

   apparently 
  homogeneous, 
  except 
  for 
  the 
  nuclei, 
  which 
  enter 
  into 
  its 
  

   composition, 
  and 
  appear 
  in 
  stained 
  preparations 
  as 
  dark 
  bodies 
  project- 
  

   ing 
  above 
  the 
  general 
  level 
  of 
  the 
  membrane, 
  which, 
  in 
  short, 
  very 
  

   closely 
  resembles 
  the 
  tunica 
  propria 
  of 
  the 
  Malpighian 
  tubes. 
  In 
  the 
  

   interior 
  of 
  the 
  cord 
  are 
  numerous 
  granular 
  oval 
  nuclei 
  (Fig. 
  61 
  ch.), 
  their 
  

   long 
  axes 
  being 
  nearly 
  parallel 
  with 
  that 
  of 
  the 
  cords. 
  If 
  a 
  cord 
  be 
  

   teazed 
  out 
  with 
  needles, 
  each 
  nucleus 
  is 
  found 
  to 
  lie 
  in 
  the 
  middle 
  of 
  a 
  

   spindle-shaped 
  body, 
  from 
  either 
  end 
  of 
  which 
  a 
  thread-like 
  process 
  runs 
  

   out 
  lengthwise 
  of 
  the 
  cord. 
  In 
  what 
  manner 
  these 
  threads 
  terminate 
  

   I 
  do 
  not 
  know. 
  This 
  cord 
  runs 
  to 
  the 
  rounded 
  tip 
  of 
  the 
  ovarian 
  tube, 
  

   which 
  begins 
  quite 
  abruptly, 
  quickly 
  attaining 
  twice 
  the 
  diameter 
  of 
  the 
  

   cord 
  in 
  Anabrus 
  (Fig. 
  64), 
  or 
  three 
  or 
  four 
  times 
  in 
  the 
  locusts. 
  From 
  

   the 
  tip 
  downwards 
  the 
  tube 
  is 
  divided 
  into 
  compartments, 
  each 
  of 
  which 
  

   contains 
  a 
  single 
  egg. 
  The 
  lower 
  we 
  go, 
  the 
  wider 
  the 
  tube 
  and 
  the 
  

   more 
  advanced 
  in 
  development 
  the 
  egg. 
  Between 
  every 
  two 
  fully- 
  

   developed 
  compartments 
  the 
  tube 
  is 
  somewhat 
  constricted. 
  In 
  Anabrus, 
  

   a 
  long 
  narrow 
  piece 
  sometimes 
  intervenes 
  between 
  two 
  adjacent 
  com- 
  

   partments. 
  In 
  locusts, 
  at 
  least, 
  the 
  tubes 
  are 
  narrowed 
  by 
  a 
  marked 
  

   constriction 
  just 
  before 
  they 
  open 
  into 
  the 
  oviduct. 
  In 
  Anabrus 
  (Fig. 
  

   CI 
  a), 
  the 
  commencement 
  of 
  the 
  upper 
  end 
  of 
  the 
  ovarian 
  tube 
  proper 
  is 
  

   marked 
  by 
  the 
  transverse 
  direction 
  of 
  a 
  few 
  oval 
  nuclei. 
  Immediately 
  

   below 
  these 
  are 
  found 
  rounded 
  nuclei, 
  and 
  among 
  them 
  lie 
  a 
  few 
  cells 
  

   which 
  have 
  already 
  assumed 
  the 
  distinctive 
  characters 
  of 
  eggs 
  ; 
  these 
  

   latter 
  cells 
  are 
  larger 
  the 
  lower 
  their 
  position. 
  In 
  this 
  part 
  of 
  the 
  tube 
  

   (Fig. 
  61 
  a 
  b) 
  there 
  is 
  no 
  distinct 
  division 
  into 
  compartments. 
  The 
  cor- 
  

   responding 
  region 
  in 
  locusts 
  differs 
  in 
  that 
  at 
  the 
  upper 
  end 
  or 
  very 
  tip 
  

   I 
  could 
  distinguish 
  only 
  one 
  kind 
  of 
  cells, 
  which 
  had 
  clear 
  nuclei 
  and 
  

   distinct 
  nucleoli. 
  Lower 
  down 
  some 
  of 
  the 
  cells 
  become 
  larger 
  than 
  

   their 
  fellows, 
  and 
  partly 
  surrounded 
  by 
  them 
  ; 
  still 
  lower 
  the 
  large 
  cells 
  

   appear 
  isolated, 
  larger, 
  and 
  completely 
  inclosed 
  by 
  a 
  layer 
  of 
  cells 
  that 
  

   form 
  a 
  perfect 
  epithelial 
  follicular 
  wall. 
  

  

  The 
  remaining 
  lower 
  and 
  largest 
  part 
  of 
  the 
  ovarian 
  tubes 
  is 
  divided 
  

   into 
  distinct 
  compartments 
  or 
  follicles. 
  As 
  we 
  proceed 
  downward 
  in 
  

   our 
  examination 
  of 
  the 
  tube 
  we 
  see 
  that 
  the 
  egg-cells, 
  which 
  were 
  at 
  

   first 
  spherical, 
  become 
  elongated 
  in 
  the 
  direction 
  of 
  the 
  axis 
  of 
  the 
  tube, 
  

   while 
  at 
  the 
  same 
  time 
  the 
  nucleus 
  becomes 
  indistinct, 
  and 
  the 
  proto- 
  

   plasm 
  of 
  the 
  original 
  cell 
  charged 
  with 
  yolk 
  granules, 
  the 
  deutoplasm 
  

   of 
  £douard 
  van 
  Beneden. 
  270 
  

  

  It 
  will 
  thus 
  be 
  seen 
  that 
  the 
  development 
  of 
  the 
  eggs 
  in 
  Caloptenus 
  

  

  269 
  Leydig 
  : 
  Zuni 
  feineren 
  Ban 
  der 
  Arthropoden. 
  Miiller's 
  Archiv., 
  1855, 
  p. 
  472-3. 
  

  

  270 
  Composition 
  et 
  Signification 
  de 
  lceuf. 
  Mem. 
  cour. 
  Academie 
  Royale 
  Belg., 
  T. 
  xsxiv, 
  p 
  1 
  (1870.) 
  

  

  