﻿312 
  W. 
  BLAXLAND 
  BENUAM. 
  

  

  ill 
  the 
  affirmative 
  ; 
  if, 
  that 
  is 
  to 
  say, 
  the 
  nephridia 
  in 
  this 
  

   worm 
  do 
  act 
  in 
  these 
  two 
  segments 
  as 
  sperm-ducts, 
  then 
  the 
  

   question 
  as 
  to 
  the 
  homology 
  of 
  these 
  ducts 
  with 
  nephridia 
  in 
  

   the 
  class 
  is 
  to 
  some 
  degree 
  reopened.^ 
  

  

  I 
  limit 
  myself 
  to 
  the 
  sperm-ducts, 
  for 
  tliere 
  is 
  no 
  resem- 
  

   blance 
  between 
  the 
  oviduct 
  and 
  the 
  nephridium, 
  and 
  there 
  

   need 
  be 
  no 
  debate 
  as 
  to 
  the 
  homology 
  between 
  these. 
  For 
  

   it 
  does 
  not 
  necessarily 
  follow 
  that 
  if 
  the 
  sperm-duct 
  be 
  

   shown 
  to 
  be 
  homologous 
  with 
  the 
  nephridium, 
  the 
  oviduct 
  

   would 
  also 
  be 
  homologous 
  ; 
  in 
  point 
  of 
  fact, 
  Vejdovsky 
  (loc. 
  

   cit,, 
  p. 
  158) 
  expressly 
  states 
  tliat 
  '' 
  there 
  is 
  not 
  a 
  complete 
  

   homology 
  between 
  the 
  oviducts 
  and 
  the 
  sperm-ducts." 
  And 
  

   further, 
  it 
  is 
  worthy 
  of 
  note 
  that 
  Biirger 
  (10), 
  in 
  a 
  recent 
  

   paper 
  on 
  the 
  development 
  of 
  Clepsine, 
  finds 
  consideiable 
  

   difference 
  in 
  the 
  mode 
  of 
  development 
  of 
  the 
  male 
  and 
  

   female 
  organs 
  in 
  the 
  Hirudinea. 
  He 
  shows 
  that 
  in 
  the 
  

   case 
  of 
  the 
  female 
  organs 
  the 
  entire 
  apparatus, 
  both 
  gonads 
  

   and 
  ducts, 
  is 
  derived 
  from 
  a 
  V-shaped 
  '' 
  anlage 
  " 
  ; 
  whereas 
  

   only 
  the 
  terminal 
  portion 
  of 
  the 
  male 
  duct 
  is 
  derived 
  from 
  

   a 
  corresponding 
  V-shaped 
  "anlage" 
  in 
  its 
  segment, 
  while 
  the 
  

   testes, 
  vasa 
  efferentia 
  and 
  v. 
  deferentia 
  develop 
  from 
  quite 
  

   independent 
  groups 
  of 
  cells, 
  which 
  are 
  not 
  represented 
  in 
  

   the 
  female 
  system. 
  We 
  may 
  therefore, 
  without 
  prejudice 
  to 
  

   the 
  larger 
  question, 
  confine 
  ourselves 
  for 
  the 
  moment 
  to 
  the 
  

   sperm-duct. 
  

  

  It 
  is 
  unnecessary 
  to 
  recapitulate 
  in 
  detail 
  all 
  the 
  points 
  of 
  

   resemblance 
  and 
  the 
  few 
  points 
  ot" 
  difference 
  exhibited 
  by 
  

   the 
  sperm-duct 
  and 
  the 
  nephridium 
  in 
  the 
  Oligoch^ta 
  in 
  

   general, 
  or 
  to 
  repeat 
  the 
  historical 
  arguments 
  and 
  views 
  of 
  

   Claparede 
  and 
  of 
  Lankester 
  in 
  support 
  of 
  the 
  homology 
  ; 
  

   for 
  this 
  has 
  been 
  recently 
  given 
  by 
  Beddard 
  in 
  his 
  account 
  

   of 
  the 
  development 
  of 
  Octochsetus 
  multiporus 
  (7). 
  It 
  

   is 
  sufficient 
  to 
  note 
  that 
  many 
  modern 
  zoologists 
  have 
  

   withdrawn 
  their 
  adherence 
  to 
  the 
  theory 
  involving 
  any 
  such 
  

   homology, 
  owing 
  to 
  the 
  facts 
  recorded 
  in 
  recent 
  embryolo- 
  

   gical 
  memoirs; 
  while 
  the 
  whole 
  subject 
  of 
  "nephridium" 
  

  

  ' 
  See 
  postscript, 
  |i. 
  322. 
  

  

  