﻿94 
  E. 
  J. 
  ALLEN. 
  

  

  surface 
  of 
  the 
  anterior 
  segments 
  (PI. 
  9, 
  fig. 
  20). 
  In 
  

   preparations 
  stained 
  with 
  methyl-blue-eosin 
  the 
  cuticle 
  is 
  

   coloured 
  blue, 
  a 
  thin 
  outer 
  layer 
  being 
  distinguishable 
  by 
  its 
  

   very 
  dark 
  colour 
  from 
  the 
  main 
  body 
  of 
  cuticular 
  substance, 
  

   which 
  is 
  staiued 
  uniformly 
  of 
  a 
  much 
  lighter 
  shade. 
  The 
  

   protoplasm 
  of 
  the 
  epithelial 
  cells 
  is 
  verj' 
  distinctly 
  granular 
  in 
  

   preparations 
  preserved 
  in 
  Hermann's 
  fluid, 
  and 
  the 
  divisions 
  

   between 
  the 
  individual 
  cells 
  are 
  often 
  strongly 
  marked. 
  Each 
  

   cell 
  contains 
  a 
  spherical 
  nucleus 
  with 
  a 
  well-marked 
  unclear 
  

   membrane. 
  Within 
  the 
  nucleus 
  is 
  one 
  large 
  mass 
  of 
  deeply 
  

   staining 
  chromatin 
  and 
  a 
  few 
  small, 
  scattered 
  particles 
  of 
  the 
  

   same 
  substance. 
  The 
  nucleus 
  as 
  a 
  whole 
  has 
  an 
  exceptionally 
  

   clear 
  and 
  transjjarent 
  appearance 
  in 
  preparations 
  preserved 
  in 
  

   Hermann's 
  fluid. 
  The 
  internal 
  ends 
  of 
  the 
  cells 
  appear 
  to 
  be 
  

   in 
  immediate 
  contact 
  with 
  the 
  muscular 
  layers 
  of 
  the 
  body- 
  

   wall. 
  Towards 
  the 
  tail 
  end 
  of 
  the 
  animal 
  the 
  epithelium 
  of 
  

   the 
  dorsal 
  surface 
  becomes 
  more 
  flattened, 
  the 
  individual 
  cells 
  

   are 
  less 
  clearly 
  marked, 
  and 
  the 
  nuclei 
  are 
  transversely 
  oval 
  

   (PL 
  10, 
  fig. 
  23). 
  

  

  On 
  the 
  ventro-lateral 
  surfaces 
  of 
  the 
  body 
  the 
  epithelial 
  

   cells 
  are 
  generally 
  more 
  elongated 
  in 
  a 
  direction 
  perpendicular 
  

   to 
  the 
  body 
  surface 
  (PI. 
  9, 
  fig. 
  21 
  ; 
  PI. 
  10, 
  fig. 
  22), 
  and 
  have 
  

   oval 
  nuclei 
  in 
  which 
  the 
  chromatin 
  is 
  present 
  in 
  the 
  form 
  of 
  a 
  

   number 
  of 
  deeply 
  staining 
  particles 
  connected 
  by 
  a 
  network, 
  

   no 
  one 
  particle 
  standing 
  out 
  so 
  prominently 
  as 
  the 
  large 
  

   single 
  mass 
  of 
  chromatin 
  in 
  the 
  nuclei 
  of 
  the 
  cubical 
  cells 
  of 
  

   the 
  dorsal 
  surface. 
  In 
  certain 
  spots 
  the 
  elongation 
  of 
  the 
  

   cells 
  is 
  very 
  great, 
  and 
  some 
  of 
  the 
  cells 
  have 
  inigrated 
  

   inwards, 
  so 
  that 
  an 
  internal 
  layer 
  of 
  nuclei 
  can 
  be 
  recognised 
  

   (fig. 
  21). 
  In 
  this 
  way 
  a 
  pad 
  or 
  cushion 
  of 
  cells 
  is 
  produced, 
  

   and 
  this 
  cushion 
  forms 
  the 
  }5oint 
  of 
  insertion 
  of 
  certain 
  muscle- 
  

   bands. 
  

  

  Epithelial 
  Gland-cells. 
  

  

  Griand-cells 
  opening 
  externally 
  by 
  means 
  of 
  short, 
  chitiuous 
  

   tubes 
  which 
  project 
  beyond 
  the 
  general 
  surface 
  of 
  the 
  body 
  

  

  