﻿316 
  W. 
  BLAXLAND 
  BRNHAM. 
  

  

  three 
  or 
  four 
  cells 
  more 
  or 
  less 
  fused 
  to 
  form 
  a 
  syncytium 
  ; 
  

   and 
  Roule 
  considers 
  it 
  certain 
  that 
  the 
  sperm- 
  duct 
  is 
  nothing 
  

   else 
  than 
  the 
  nephridium 
  of 
  this 
  twelfth 
  segment, 
  Avhich 
  is 
  

   late 
  in 
  appearing, 
  for 
  its 
  special 
  function 
  is 
  not 
  called 
  into 
  

   play 
  till 
  a 
  much 
  later 
  stage 
  than 
  that 
  of 
  the 
  segmental 
  organ. 
  

  

  It 
  will 
  be 
  noted 
  that 
  this 
  is 
  a 
  very 
  different 
  history 
  from 
  

   that 
  given 
  by 
  Vejdovsky 
  ; 
  and 
  it 
  is 
  well 
  to 
  note 
  that 
  Roule 
  

   studied 
  sections 
  through 
  successive 
  stages, 
  whereas 
  it 
  appears 
  

   from 
  Vejdovsky's 
  words 
  that 
  he 
  studied 
  living- 
  specimens 
  and 
  

   entire 
  preparations 
  only. 
  

  

  Then 
  follows 
  Beddard 
  (7), 
  who 
  dealt 
  with 
  a 
  " 
  micro- 
  

   nephric 
  " 
  earthworm, 
  Octochretus 
  multiporus, 
  a 
  form 
  in 
  

   which 
  the 
  earliest 
  segmental 
  organ 
  is 
  a 
  " 
  meganephridium," 
  

   which 
  becomes 
  broken 
  up 
  into 
  a 
  number 
  of 
  micro-nephridia 
  

   which 
  are 
  without 
  funnels. 
  According 
  to 
  this 
  author 
  the 
  

   original 
  funnel 
  of 
  the 
  meganephridium 
  persists 
  in 
  the 
  genital 
  

   segments, 
  and 
  becomes 
  converted 
  into 
  the 
  genital 
  funnel 
  in 
  

   each 
  case 
  ; 
  whilst 
  the 
  genital 
  duct 
  is 
  for 
  the 
  first 
  part 
  of 
  its 
  

   course 
  derived 
  from 
  part 
  of 
  the 
  nephridium, 
  which 
  starts 
  to 
  

   grow 
  once 
  more, 
  and 
  extends 
  back 
  to 
  form 
  the 
  rest 
  of 
  the 
  

   genital 
  duct 
  (p. 
  578). 
  

  

  If, 
  now, 
  we 
  consider 
  these 
  various 
  statements, 
  and 
  if 
  we 
  

   regard, 
  as 
  I 
  believe 
  most 
  zoologists 
  will 
  do, 
  the 
  "Limicoline" 
  

   Oligochaetes 
  as 
  ancestral 
  to 
  the 
  " 
  Terricoline," 
  it 
  seems 
  pro- 
  

   bable 
  that, 
  phylogenetically, 
  the 
  history 
  of 
  affairs 
  with 
  regard 
  

   to 
  the 
  organ 
  under 
  discussion 
  has 
  been 
  somewhat 
  as 
  follows 
  : 
  

  

  First 
  stage.— 
  The 
  nephridia 
  act 
  as 
  genital 
  ducts, 
  for 
  Stole 
  

   (14) 
  findsthatin 
  Aeolosoma 
  spei'matozoamay 
  escapefroiuall 
  

   or 
  any 
  of 
  the 
  segmental 
  organs 
  ; 
  in 
  the 
  genital 
  segments 
  these 
  

   are 
  slightly 
  larger 
  than 
  in 
  other 
  segments, 
  though 
  otherwise 
  

   similar 
  to 
  them. 
  The 
  funnel 
  of 
  the 
  nephridium 
  is 
  of 
  very 
  

   simple 
  structure, 
  and 
  there 
  are 
  no 
  representatives 
  of 
  the 
  

   " 
  marginal 
  cells." 
  Further, 
  according 
  to 
  Roule, 
  the 
  sperm- 
  

   duct 
  is 
  a 
  late-appearing 
  nephridium 
  in 
  one 
  species 
  of 
  

   Enchytrffiid. 
  

  

  Second 
  stage. 
  — 
  A 
  special 
  coelomostome 
  becomes 
  devel- 
  

   oped, 
  which, 
  added 
  to 
  the 
  nephridium, 
  increases 
  the 
  eflSciency 
  

  

  