﻿SOME 
  NEW 
  SPECIES 
  OP 
  THE 
  GENUS 
  PHREODRILUS. 
  289 
  

  

  of 
  tlie 
  fibres 
  are 
  cut 
  across 
  without 
  either 
  terminal 
  being- 
  

   involved, 
  the 
  appearance 
  may 
  suggest 
  bundles 
  of 
  sperma- 
  

   tozoa^ 
  especially 
  as 
  the 
  cut 
  ends 
  — 
  facing 
  the 
  microscope 
  — 
  

   have 
  a 
  greater 
  refringency 
  than 
  the 
  more 
  horizontal 
  portions, 
  

   and 
  suggest 
  "heads'' 
  (fig. 
  23 
  rm'.). 
  

  

  It 
  is 
  possible 
  that 
  these 
  delicate 
  fibres, 
  radiating 
  in 
  groups 
  

   m 
  every 
  direction 
  across 
  the 
  cavity 
  of 
  the 
  sac, 
  may 
  have 
  been 
  

   mistaken 
  for 
  sperms; 
  yet 
  I 
  hesitate 
  to 
  assume 
  that 
  an 
  error 
  of 
  

   this 
  kind 
  would 
  be 
  made 
  by 
  so 
  accurate 
  and 
  experienced 
  

   an 
  observer 
  as 
  my 
  friend 
  Mr. 
  Beddard. 
  I 
  merely 
  suggest 
  

   this 
  explanation 
  of 
  the 
  mystery, 
  for 
  he 
  himself 
  admits 
  it 
  is 
  

   a 
  mystery 
  that 
  surrounds 
  their 
  presence 
  in 
  this 
  completely 
  

   closed 
  sac 
  ; 
  the 
  more 
  so 
  as 
  it 
  appears 
  to 
  me 
  that 
  the 
  relative 
  

   size 
  of 
  "head" 
  to 
  "tail" 
  indicated 
  in 
  his 
  figures 
  is 
  not 
  that 
  

   usual 
  to 
  the 
  sperms 
  of 
  Oligochasta. 
  

  

  The 
  atrium 
  itself 
  exhibits 
  two 
  regions, 
  distinguishable 
  by 
  

   the 
  character 
  of 
  the 
  epithelium, 
  though 
  not 
  otherwise. 
  The 
  

   upper 
  region 
  (fig. 
  22 
  at.) 
  closely 
  resembles 
  the 
  sperm-duct, 
  

   and 
  corresponds 
  with 
  the 
  narrow 
  white 
  tube 
  in 
  Beddard's 
  

   species 
  ; 
  the 
  lower 
  region 
  is 
  cuticulated, 
  and 
  otherwise 
  con- 
  

   trasts 
  with 
  the 
  sperm-duct, 
  and 
  resembles 
  the 
  shaded 
  portion 
  

   ("atrium") 
  of 
  Beddard's 
  figure 
  7. 
  

  

  The 
  epithelium 
  of 
  the 
  upper 
  region 
  is 
  finely 
  granular 
  ; 
  no 
  cell 
  

   outlines 
  are 
  visible, 
  and 
  the 
  round 
  nuclei 
  — 
  more 
  deeply 
  staining 
  

   than 
  in 
  the 
  case 
  of 
  the 
  vas 
  deferens 
  — 
  are 
  few 
  and 
  regularly 
  

   spaced. 
  The 
  lumen 
  is 
  fairly 
  large, 
  and 
  shows 
  most 
  distinctly 
  

   cilia. 
  It 
  might 
  be 
  suggested 
  that 
  these 
  are 
  in 
  reality 
  sperma- 
  

   tozoa 
  passing 
  down 
  the 
  canal 
  ; 
  but 
  against 
  this 
  interpretation 
  

   are 
  the 
  facts, 
  firstly, 
  that 
  many 
  of 
  them 
  are 
  arranged, 
  verti- 
  

   cally 
  to 
  the 
  surface 
  of 
  the 
  cells, 
  from 
  which 
  they 
  can 
  be 
  seen 
  

   arising, 
  and 
  secondl}'-, 
  the 
  failure 
  to 
  discover 
  any 
  heads, 
  

   which 
  would 
  of 
  course 
  appear 
  as 
  fairly 
  deeply 
  stained 
  points; 
  

   but 
  nothing 
  of 
  the 
  sort 
  occurs. 
  

  

  There 
  appears 
  to 
  be 
  no 
  circular 
  muscle-fibres 
  round 
  the 
  

   ati'ium 
  ; 
  for 
  in 
  such 
  sections 
  as 
  cut 
  it 
  longitudinally 
  or 
  nearly 
  

   so 
  I 
  cannot 
  detect 
  any 
  cut 
  ends 
  of 
  fibres, 
  but 
  outside 
  the 
  

   epithelium 
  is 
  a 
  layer 
  of 
  muscle-fibres, 
  with 
  which 
  the 
  radiat- 
  

  

  