108  DE.  T.  WILLIAMS’S  EESEAECHES  ON  THE  STEUCTEEE  AXD  HOMOLOGY 
At  this  stage  of  the  dissection,  it  may  be  easily  obseiTed  that  each  segmental  space 
has  its  own  distinct  and  independent  cihated  tube. 
On  further  examination  it  will  be  seen  that  it  is  around  the  bases  or  attached  ends  of 
these  tubes  that  the  reproductive  masses  cluster. 
The  ovarian  and  testicular  masses  are  definitely  bounded  by  the  dissepiments  {j,  j,  j). 
The  roots  of  these  bodies  are  always  situated  within  the  space  of  its  own  segment ; but 
the  body  of  the  larger  glands  (as  c and  ^)  may  from  their  size  extend  across  several 
segments. 
These  few  leading  statements  explain  the  principle  on  which  the  sexual  system  of  In/.m- 
briciis  is  constructed.  (Fig.  6 represents  the  entire  system  in  the  condition  of  its  greatest 
development.) 
Before  proceeding  to  the  minute  dissection  of  these  parts,  the  position  of  the  thickened 
collar,  so  prominently  observed  on  the  external  surface,  with  respect  to  that  of  the  gene- 
rative masses  within,  should  be  particularly  noticed.  It  will  be  seen  to  be  placed,  by 
several  segments,  behind  these  masses.  This  thickened  ring  is  bounded  by  sharp  borders 
before  and  behind.  It  involves  six  or  eight  annuli  of  the  integuments.  On  its  abdo- 
minal surface  two  suctorial  cups  are  observable.  It  is  most  certain  that  these  cups  are 
not  perforated  at  the  bottom ; they  cannot  therefore  be,  as  supposed  by  some  anatomists, 
the  outlets  of  certain  tubes  within*.  They  are  in  truth  designed  only  to  hold  the  indi- 
vidual in  apposition  during  the  generative  congress.  That  there  is  no  organic  connexion 
between  these  cups  and  the  reproductive  masses,  may  be  further  proved  by  carefully 
examining  (internally)  (previously  dissecting  away  the  intestine)  the  condition  of  the 
ciliated  tubes  in  the  intervening  segments.  They  are  not  developed  like  those  in  the 
generative  segments;  they  belong  to  the  class  of  the  “ordinary”  segmental  organs. 
These  intervening  annuli  are  not  crossed  in  this  worm,  as  described  and  figm'ed  by 
Herixg  in  Lmnbricus  agricola,  by  the  vasa  deferentia  and  oviducts.  In  fact  they  are 
altogether  excluded  from,  and  beyond  the  limits  of  the  reproductive  segments. 
Now,  in  studying  the  visceral  contents  of  each  ring  within  the  limits  of  the  generative 
region,  it  will  be  best  to  proceed  from  behind  forwards. 
The  dissector  thus  comes  first  upon  the  largest  and  most  prominent  (fig.  6,  i,  i)  of  all 
the  generative  masses.  They  are  testes.  This  can  only  be  proved  by  the  examination 
of  the  products  contained  within  them,  under  the  microscope.  They  have  a white, 
glittering,  oily  colour.  In  figure  they  are  intestiform,  the  coils,  of  which  there  are  two 
or  three,  being  tied  together  by  means  of  a mesentery.  The  capsule  consists  of  a proper 
membranous  tunic,  and  is  seen  to  be  thinly  supplied  with  vessels  when  carefully  floated 
and  suspended  in  water ; these  two  testicular  masses,  which  lie  across  and  fill  up  several 
* The  distance  internally  between  the  tegumentary  ring  and  the  generative  masses  is  represented  hy 
Ewald  Heeixg  (Zeitsch.  f.  W.  Zool.  Nov.  12,  1856)  as  traversed,  in  Lumlrictis  agricola,  by  the  oviducts 
and  vasa  deferentia.  The  most  carefully  repeated  dissections  have  convinced  me  that  neither  of  these  ducts 
exist  in  Lvmhricus  terrestris.  If  they  have  no  existence  in  this  species,  it  is  highly  probable  that  Heking 
has  been  led  into  error  in  describing  them  in  Lv/mbricm  agricola. 
