﻿THE 
  ANATOMY 
  OF 
  P(EOILOOHJiTUS, 
  CLAPAKEDE. 
  118 
  

  

  body- 
  cavity 
  of 
  the 
  first 
  segment 
  of 
  the 
  worm. 
  The 
  space 
  

   between 
  this 
  central 
  canal 
  and 
  the 
  epidermis 
  is 
  filled 
  with 
  an 
  

   irregular 
  mass 
  of 
  cells, 
  forming 
  a 
  loose 
  tissue, 
  in 
  which 
  may 
  

   be 
  seen 
  many 
  of 
  the 
  spherical 
  bodies 
  filled 
  with 
  granules 
  

   mentioned 
  in 
  the 
  last 
  paragraph. 
  Figs. 
  40 
  and 
  41 
  (PI. 
  11), 
  

   representing 
  respectively 
  a 
  transverse 
  section 
  through 
  one 
  of 
  

   the 
  ciliated 
  grooves 
  and 
  an 
  enlarged 
  section 
  of 
  a 
  portion 
  of 
  

   the 
  epithelium 
  of 
  a 
  groove, 
  show 
  the 
  minute 
  structure 
  of 
  the 
  

   tissue 
  of 
  the 
  nuchal 
  organ. 
  The 
  epidermis, 
  excepting 
  in 
  the 
  

   ciliated 
  grooves 
  themselves, 
  consists 
  of 
  low 
  epithelial 
  cells 
  

   crowded 
  with 
  dark-coloured 
  granules, 
  the 
  granules 
  being 
  in 
  

   many 
  places 
  congregated 
  into 
  masses 
  of 
  considerable 
  size. 
  

   The 
  epithelial 
  cells 
  are 
  covered 
  externally 
  by 
  a 
  layer 
  of 
  

   cuticle 
  resembling 
  the 
  general 
  body 
  cuticle. 
  No 
  gland-cells, 
  

   such 
  as 
  have 
  been 
  described 
  in 
  other 
  parts 
  of 
  the 
  body, 
  have 
  

   been 
  observed 
  in 
  the 
  nuchal 
  organ. 
  

  

  The 
  ciliated 
  epithelial 
  cells 
  of 
  the 
  grooves 
  are 
  very 
  large 
  

   and 
  much 
  elongated, 
  the 
  protoplasm 
  of 
  the 
  bodies 
  of 
  the 
  cells 
  

   is 
  filled 
  with 
  dark 
  granules 
  similar 
  to 
  those 
  found 
  elsewhere 
  

   in 
  the 
  organ, 
  and 
  the 
  large 
  oval 
  nuclei 
  lie 
  near 
  the 
  bases 
  of 
  

   the 
  cells, 
  their 
  long 
  axes 
  being 
  parallel 
  to 
  the 
  long 
  axes 
  of 
  

   the 
  cells. 
  The 
  structure 
  of 
  the 
  external 
  or 
  ciliated 
  ends 
  of 
  

   the 
  cells 
  presents 
  features 
  of 
  interest, 
  and 
  can 
  be 
  seen 
  from 
  

   figs. 
  40 
  and 
  41. 
  The 
  cuticle 
  (c?^ 
  g.) 
  covering 
  the 
  cells 
  under- 
  

   goes 
  a 
  very 
  considerable 
  external 
  thickening. 
  In 
  sections 
  

   stained 
  with 
  methyl-blue-eosin 
  the 
  basal 
  portion 
  only 
  of 
  this 
  

   cuticle 
  stains 
  a 
  deep 
  blue, 
  carrying 
  on 
  the 
  line 
  of 
  the 
  general 
  

   cuticle 
  of 
  the 
  nuchal 
  organ 
  ; 
  the 
  external 
  thickened 
  portion 
  

   remains 
  clear 
  and 
  unstained 
  {cu. 
  <y.), 
  and 
  in 
  favourable 
  places 
  

   is 
  seen 
  to 
  be 
  traversed 
  by 
  a 
  series 
  of 
  faint 
  lines 
  running 
  at 
  

   right 
  angles 
  to 
  its 
  surface. 
  Since 
  these 
  lines 
  are 
  much 
  more 
  

   widely 
  separated 
  than 
  the 
  cilia, 
  they 
  would 
  seem 
  not 
  to 
  be 
  due 
  

   to 
  the 
  cilia 
  passing 
  through 
  the 
  cuticle. 
  Racovitza 
  (1896) 
  

   has 
  described 
  a 
  very 
  similar 
  thickening 
  of 
  the 
  cuticle 
  in 
  the 
  

   caruncle 
  of 
  Euphrosyne 
  Audouini. 
  In 
  the 
  case 
  of 
  that 
  

   worm, 
  however, 
  the 
  thickening 
  does 
  not 
  extend 
  over 
  the 
  

   areas 
  of 
  cuticle 
  lying 
  just 
  above 
  the 
  ciliated 
  cells. 
  

  

  