114  DE.  T.  WILLIAMS’S  EESEAECHES  ON  THE  STEHCTUEE  AND  HOMOLOGY 
But  notwithstanding  this  morphological  affinity,  a remarkable  difference  obtains 
between  the  segmental  organs  of  the  Hirudinei  and  those  of  Lumbricini,  as  will  after- 
wards appear. 
In  Hffudo  officinalis  and  Albione  mmicata  every  segmental  organ  in  tli.e  body  is  not 
only  an  excretionary  instrument  for  the  discharge  of  the  cavitary  fluid,  hut  is  also  an  ovary*. 
lung  der  Eaderthiere,”  Zeitsch.  f.  Wiss.  Zool.  1854),  represents  the  present  state  of  knowledge  on  this  sub- 
ject, it  is  here  transcribed: — “ Der  beschriebene  Eespirationsapparat  der  Eotifera  hat,  vom  morphologischen 
uud  histologischen  Standpnnkt  aus  angesehen,  die  grbsste  Aehnlichkeit  mit  jenen  organen,  welche  bei  Lurn- 
Iricinen  und  Hirudinen  als  Athmungsorgane  gelten.  Auch  bei  ihnen  kommen  geschlangelte  und  genauelte 
Ebhren  vor  mit  heUem  Lumen,  die  sich  entweder  ohne  Blase  nach  aussen  bffnen  (z.  B.  Clepsine)  oder  rorher 
in  eine  contractile  Blase  miinden  (z.  B.  Nephelis).  Nach  innen  miindet  der  Kanal  mit  einer  erweiterten 
und  bewimperten  Oeffnung  in  die  Leibeshbhle  aus.  Ich  sehe  in  diesem  Endstiick  der  Ebhren  das  Aualogon 
der  ‘ Zitterorgane  ’ der  Eaderthiere  und  auch  die  Wimperrichtung  geht  bei  den  Anneliden  nach  einwarts  in 
den  Kanal.  Eine  schbne  Darstellung  von  der  innern  Miindung  des  Eespirationskanal  beim  Eegenwurm  gibt 
Geuenbauee,  und  vide  ich  schon  an  einem  andern  Orte  (Mullee,  Archiv,  1852)  ausgesprochen,  so  bin  ich 
der  Ansicht,  dass  das  ‘ arabeskenfbrmige  Organ  der  Nephelis  und  das  rosettenfbrmige  Wimperorgan  der 
Clepsine,'  worauf  auch  bereits  Gegenbatjee  angespiel  that,  nichts  weiteres  sind,  als  die  Endstiicke  der  Ee- 
spirationskanal dieser  Hirudineen.  V on  gleicher  Bedeutung  halte  ich  die  eigenthiimlichen  ‘ pantoffel-  und 
fuUhornfbrmigen  organe  ’ der  Synapta  digitata  seiche  Joh.  Muelee  (Archiv,  1852)  aufgefunden  und  deren 
feine  Cihen  ebenfalls  nach  einwarts  schlagen.”  Letdig  then  proceeds  to  argue  in  favour  of  the  respiratory 
function  (!)  of  these  organs,  opposing  the  ideas  of  Gegenbaeee,  BEEGMAjm  and  Leeeaet,  who  in  Lnin- 
iricus  attribute  to  the  ciliated  tubes  the  office  of  kidneys. 
It  should  be  here  stated,  that  in  1852  (Annal.  des  Sc.  Nat.  t.  28.  p.  175)  De  Qtjateeeages,  although 
unacquainted  with  the  real  miaute  anatomy  of  these  organs,  yet  hints  at  the  analogy  between  those  of  Lum- 
hricus  and  Hirudo.  “ Les  poches  laterales  des  Sangsues,  evidemment  analogues  aux  canaux  tortueux  des 
Lombrics,  ont  ete  considerees,  soit  comme  des  organes  de  respiration  (Dtjges  et  quelques  autres  anato- 
mistes),  soit  comme  des  organes  de  secretion  devant  fournir,  plus  particulierement  que  d’autres  glandes,  la 
mucosite  qui  enduit  le  corps  de  I’animal.  J’ai  embrasse  cette  derniere  opinion,”  &c And  he  embraces 
this  opinion  knowing  the  views  which  I had  then  published,  for  he  observes,  “ M.  Williams  Medecin  an- 
glais, qui  a public  un  rapport  fort  etendu  sur  I’Anatomie  des  Annehdes,  vient  d’emettre  une  opinion  toute 
nouveUe.  II  regarde  ces  poches  et  ces  canaux  comme  faisant  partie  des  organes  reproducteurs  femelles  des 
Sangsues  et  des  Lombrics.”  It  will  be  seen  that,  with  respect  to  the  female  system  of  Lumhricus,  the  re- 
sults published  in  this  paper  differ  in  some  points  from  those  given  in  my  Eeport,  to  which  De  Qbatee- 
EAGES  alludes.  My  former  and  my  recent  researches  differ,  however,  only  in  this  particular,  that  whereas  I 
formerly  described  every  “ segmental  organ  ” in  the  body  as  an  ovary,  more  extended  study  has  conidnced 
me  that  under  normal  circumstances  in  the  'Earth-worm  only  a few  of  these  organs  become  developed  into 
ovaries.  In  the  Common  Leech  and  the  Sea-leech  the  entire  lateral  series  of  the  segmental  organs  of  the 
body,  I still  maintain,  are  ovarian. 
It  appears,  therefore,  that  to  Gegestbahee  is  due  the  merit  of  having  first  suggested  the  analogy  between 
the  segmental  organ  of  Clepsina  and  Nephelis  and  that  of  the  Earth-worm.  This  suggested  analogy  has 
been  further  extended  by  Leydig.  By  neither  of  these  observers,  however,  has  the  slightest  allusion  been 
made  to  the  connexion  which  exists  between  these  organs  and  the  reproductive  system  in  these  Annelids. 
* I have  made  very  numerous  examinations  on  species  of  Clepsina  and  JVephelis  which  inhabit  the  pools 
of  this  neighbourhood  (Swansea),  with  a view  to  ascertain  whether  the  araheskenf dr mige"  organs,  as  de- 
scribed by  Letdig  in  these  genera,  contain  ova  in  every  ring  of  the  body,  as  in  the  Common  Leech  and 
Sea-leech,  or  whether  only  a few  of  these  organs,  as  in  Nais  and  Lumhricus,  experience  an  ovarian  develop- 
ment, the  rest  remaining  in  the  condition  of  mere  excretionary  tubes.  But,  in  consequence  of  the  extreme 
