﻿22 
  

  

  H. 
  S. 
  Pratt, 
  

  

  A 
  young 
  larva 
  or 
  au 
  egg 
  can 
  also 
  be 
  detected, 
  but 
  less 
  easily; 
  it 
  

   lies 
  in 
  the 
  forward 
  portion 
  of 
  tlie 
  uterus 
  and 
  appears 
  near 
  the 
  centre 
  

   of 
  the 
  abdonien. 
  

  

  In 
  its 
  finer 
  structure 
  the 
  uterus 
  presents 
  no 
  new 
  features. 
  but 
  

   sonie 
  interesting 
  modifications 
  of 
  the 
  usual 
  conditions. 
  Its 
  walls 
  are 
  

   a 
  direct 
  continuation 
  of 
  those 
  of 
  the 
  vagina. 
  The 
  thickness 
  of 
  the 
  

   cuticula 
  at 
  the 
  posterior 
  end 
  of 
  the 
  uterus 
  equals 
  that 
  of 
  the 
  cuticula 
  

   of 
  the 
  vagina, 
  but 
  this 
  thickness 
  gradually 
  diinimshes 
  toward 
  the 
  

   forward 
  end 
  and 
  in 
  its 
  forward 
  half 
  the 
  uterus 
  is 
  lined 
  by 
  such 
  an 
  

   extremely 
  thin 
  and 
  delicate 
  cuticula 
  that 
  it 
  is 
  often 
  difficult 
  to 
  detect. 
  

   The 
  niatrix 
  of 
  the 
  cuticula 
  is 
  the 
  usual 
  single-layered 
  epitheliuni. 
  

   This 
  is 
  surrounded 
  by 
  a 
  thickly 
  woven 
  layer 
  of 
  branched 
  niuscle- 
  

   fibres 
  forming 
  a 
  network 
  about 
  the 
  entire 
  uterus 
  which 
  brauch 
  without 
  

   regularity 
  and 
  are 
  of 
  varying 
  thickness 
  (PL 
  III, 
  Fig. 
  7). 
  The 
  Strands 
  

   imruediately 
  next 
  to 
  the 
  uterine 
  wall 
  appear 
  to 
  be 
  smaller 
  than 
  those 
  

   toward 
  the 
  outside. 
  The 
  function 
  of 
  this 
  network 
  is 
  evident. 
  It 
  is 
  

   primarily, 
  by 
  the 
  contraction 
  of 
  its 
  fibres, 
  to 
  bring 
  about 
  parturition 
  

   at 
  the 
  proper 
  nioment, 
  but 
  it 
  must 
  also 
  serve 
  to 
  strengthen 
  and 
  Sup- 
  

   port 
  the 
  wall 
  of 
  the 
  uterus 
  while 
  that 
  organ 
  is 
  heavy 
  with 
  the 
  

   growing 
  larva. 
  On 
  the 
  outer 
  surface 
  of 
  the 
  muscle-sheath 
  run 
  longi- 
  

   tudinal 
  bundles 
  of 
  unbranched 
  niuscle-fibres 
  which 
  connect 
  the 
  uterus 
  

   with 
  the 
  ventral 
  and 
  anterior 
  portions 
  of 
  the 
  abdominal 
  wall. 
  Also 
  

   a 
  few 
  fibres 
  pass 
  froni 
  the 
  dorsal 
  uterine 
  wall 
  around 
  the 
  rectum 
  to 
  

   the 
  dorsal 
  abdominal 
  wall. 
  The 
  most 
  important 
  of 
  these 
  longitudirial 
  

   groups 
  of 
  muscles 
  are 
  those 
  which 
  pass 
  from 
  the 
  forward 
  portions 
  

   of 
  the 
  uterus 
  to 
  the 
  anterior 
  and 
  ventral 
  abdominal 
  body-wali 
  (PL 
  IL 
  

   Fig. 
  3 
  l.mus). 
  These 
  are 
  attached 
  to 
  the 
  dorsal, 
  ventral, 
  and 
  lateral 
  

   surfaces 
  of 
  the 
  uterus 
  and 
  find 
  their 
  forward 
  attachment 
  principally 
  

   on 
  two 
  ridges 
  of 
  the 
  abdominal 
  wall 
  which 
  project 
  into 
  the 
  body- 
  

   cavity. 
  We 
  see 
  thus 
  that 
  the 
  uterus 
  is 
  provided 
  with 
  an 
  extremely 
  

   strong 
  musculature, 
  composed 
  of 
  two 
  distinct 
  Systems 
  of 
  fibres; 
  the 
  

   branched 
  fibres 
  forming 
  the 
  sheath 
  immediately 
  about 
  it 
  and 
  the 
  

   longitudinal 
  fibres 
  which 
  connect 
  it 
  with 
  the 
  body-wall. 
  The 
  function 
  

   of 
  the 
  latter 
  is 
  undoubtedly 
  to 
  hold 
  the 
  uterus 
  in 
  position. 
  They 
  

   are 
  strong 
  elastic 
  bands 
  which 
  bind 
  the 
  uterus 
  to 
  the 
  body-wall 
  but 
  

   whose 
  length 
  can 
  change 
  with 
  the 
  varying 
  size 
  of 
  the 
  uterus. 
  But 
  

   these 
  muscle-fibres 
  are 
  not 
  the 
  only 
  means 
  of 
  support 
  with 
  which 
  the 
  

   uterus 
  is 
  supplied. 
  From 
  the 
  most 
  anteriorly 
  placed 
  abdominal 
  

   spiracles 
  a 
  pair 
  of 
  strong 
  tracheal 
  trunks 
  pass 
  to 
  the 
  uterus, 
  just 
  in 
  

  

  