﻿The 
  Anatouiy 
  of 
  the 
  Feinale 
  Genital 
  Tract 
  of 
  the 
  Pupipara 
  etc. 
  35 
  

  

  phagus, 
  which 
  is 
  unusual 
  where 
  this 
  covering 
  is 
  as 
  thick 
  as 
  it 
  is 
  in 
  

   tliis 
  insect. 
  It 
  is 
  not 
  unusual 
  for 
  these 
  coverings 
  to 
  fuse 
  beyond 
  the 
  

   end 
  of 
  the 
  terminal 
  thread 
  and 
  form 
  a 
  common 
  mass 
  of 
  connective- 
  

   tissue 
  at 
  the 
  distal 
  end 
  of 
  the 
  ovary. 
  In 
  Musca, 
  this 
  fused 
  portion 
  

   contains 
  muscle-fibres, 
  and 
  it 
  seems 
  to 
  me 
  that 
  the 
  outer 
  peritoneal 
  

   sac 
  in 
  Melophagus 
  with 
  its 
  thickly 
  woven 
  layer 
  of 
  muscles 
  may 
  be 
  

   a 
  further 
  development 
  of 
  the 
  muscle 
  and 
  connective-fibres 
  which 
  in 
  

   Musca 
  are 
  present 
  at 
  the 
  distal 
  of 
  the 
  ovary. 
  In 
  no 
  other 
  insect, 
  so 
  

   far 
  as 
  I 
  know, 
  does 
  the 
  peritoneal 
  covering 
  of 
  the 
  ovarioles 
  fail 
  to 
  

   be 
  continuous 
  with 
  the 
  outer 
  covering 
  of 
  the 
  oviduct, 
  and 
  that 
  this 
  

   is 
  the 
  case 
  in 
  Melophagus 
  is 
  probably 
  due 
  to 
  the 
  fact 
  that 
  the 
  outer 
  

   covering 
  ot 
  the 
  oviduct 
  finds 
  its 
  continuation 
  in 
  the 
  peritoneal 
  sac. 
  

  

  The 
  ovarioles. 
  Each 
  ovariole 
  consists 
  of 
  a 
  short, 
  thick 
  germ- 
  

   arium 
  or 
  terminal 
  Chamber 
  and 
  one 
  or 
  two 
  follicles, 
  and 
  is 
  bounded 
  

   on 
  the 
  outside 
  by 
  a 
  delicate 
  tunica 
  propria. 
  The 
  germarium 
  in 
  a 
  

   small 
  ovary 
  is 
  about 
  0,05 
  mm 
  long 
  and 
  0,025 
  mm 
  thick 
  at 
  its 
  base, 
  

   and 
  is 
  imbedded 
  for 
  about 
  a 
  third 
  of 
  its 
  length 
  in 
  the 
  fibrous 
  mass 
  

   at 
  the 
  distal 
  end 
  of 
  the 
  peritoneal 
  sac 
  (PI. 
  III, 
  Fig. 
  12 
  ger, 
  Fig. 
  13 
  ger). 
  

   The 
  germarium 
  tapers 
  towards 
  its 
  tip 
  where 
  it 
  contains 
  but 
  one 
  or 
  

   two 
  nuclei. 
  It 
  is 
  surrounded 
  by 
  a 
  tunica 
  propria 
  to 
  its 
  tip. 
  The 
  Con- 
  

   tents 
  of 
  the 
  germarium 
  are 
  small, 
  compact 
  nuclei 
  all 
  of 
  the 
  same 
  size 
  

   and 
  appearance 
  imbedded 
  in 
  protoplasm, 
  no 
  cell-walls 
  being 
  demon^ 
  

   strahle. 
  The 
  germarium 
  is 
  separated 
  from 
  the 
  youngest 
  follicle 
  by 
  

   a 
  constriction. 
  In 
  a 
  very 
  small 
  ovary 
  the 
  smaller 
  of 
  the 
  two 
  ovar- 
  

   ioles 
  does 
  not 
  contain 
  the 
  usual 
  two 
  follicles, 
  but 
  a 
  Single 
  mass 
  of 
  

   germ-cells 
  in 
  which 
  differentiation 
  has 
  but 
  just 
  begun 
  (PI. 
  III, 
  Fig. 
  1 
  2 
  

   ovar.2). 
  The 
  first 
  signs 
  of 
  differentiation 
  in 
  the 
  young 
  follicle 
  is 
  a 
  

   division 
  of 
  its 
  cells 
  into 
  peripheral 
  and 
  central 
  cells, 
  the 
  former 
  

   being 
  smaller 
  than 
  the 
  later 
  and 
  arranged 
  in 
  a 
  regulär, 
  peripheral 
  

   layer. 
  This 
  layer 
  is 
  destined 
  to 
  become 
  the 
  follicular 
  epithelium 
  of 
  

   the 
  two 
  follicles 
  of 
  the 
  ovariole, 
  the 
  inner 
  cells 
  to 
  become 
  the 
  nu- 
  

   tritive 
  and 
  egg 
  cells. 
  Covering 
  the 
  common 
  follicle 
  is 
  a 
  tunica 
  pro- 
  

   pria, 
  which 
  does 
  not 
  end 
  at 
  its 
  lower 
  end, 
  but 
  extends 
  alougside 
  

   the 
  larger 
  ovariole 
  to 
  near 
  the 
  lower 
  end 
  of 
  the 
  ovary 
  and 
  contains 
  

   the 
  disintegrated 
  remains 
  of 
  the 
  follicle 
  which 
  last 
  discharged 
  an 
  

   ovum 
  (PI. 
  III, 
  Fig. 
  12 
  dis.fol.ce). 
  Very 
  soon 
  the 
  inner 
  cells 
  at 
  the 
  

   lower, 
  posterior 
  end 
  of 
  the 
  common 
  follicle 
  begin 
  to 
  increase 
  greatly 
  

   in 
  size; 
  the 
  extreme 
  posterior 
  one 
  of 
  these 
  cells 
  becomes 
  distinctly 
  

   different 
  in 
  appearance 
  from 
  its 
  fellows 
  and 
  somewhat 
  larger 
  than 
  

   them 
  and 
  acquires 
  a 
  nucleus 
  which 
  contains 
  far 
  fewer 
  chromatine 
  

  

  3* 
  

  

  