or  THE  EEPEODIJCTIVE  OEOAJfS  OF  THE  ANNELIDS. 
117 
It  is  noteworthy,  that  in  the  entire  family  of  the  Hirudinei  the  female  or  ovarian 
system  preponderates  considerably  in  size  and  extent  of  distribution  over  the  testicular, 
whereas  in  I^ais  and  Inimbricus  the  male  and  female  moieties  of  the  reproductive  parts 
exhibit  very  nearly  equal  proportions.  In  the  Hirudinei  the  ovaria  are  beyond  all  doubt 
identified  with  the  lateral  series  of  the  segmental  organs;  It  will  be  afterwards  inquired 
how  far  it  is  correct  to  consider  the  testes  as  also  one  or  more  of  these  organs  modified 
after  a different  model*.  Leeches  are  hermaphrodite;  but,  although  the  male  and 
female  parts  are  present  in  each  individual,  and  since  there  is  no  internal  communication 
between  these  two  parts,  the  union  of  two  different  individuals  is  necessary  to  impreg- 
nation : the  individual  is  not  fertilized  by  its  own  sperm-fluid,  but  by  that  of  another. 
The  male  system  of  the  Hirudinei  is  well  known  to  anatomists.  As  to  its  descriptive 
anatomy,  the  author  has  nothing  now  to  add.  He  is  desirous  only  to  offer  a few  obser- 
vations with  respect  to  its  homology. 
In  speaking  of  the  ovaria  it  should  have  been  stated  that  they  are  all  of  equal  size 
and  development.  It  is  however  a fact  of  singular  morphological  interest  to  note  that 
in  that  particular  annulus  at  which  the  testicular  series  converges,  or  that  from  which 
they  arise,  the  ovaria  are  wanting.  Now  it  is  only  necessary  to  suppose  that  the  two 
segmental  organs  normal  to  this  particular  annulus,  instead  of  obeying  the  rule  applying 
to  all  the  others,  experience  a special  growth  and  expansion,  giving  rise,  not  to  ovaria, 
but  to  highly  developed  and  systematically  distributed  testes,  and  the  morphologist 
is  at  once  furnished  with  the  key  by  which  he  may  unlock  the  mysteries  of  this  most 
complex  and  hitherto  incomprehensible  system  of  organs.  In  fact  the  two  series  of 
testicular  organs,  proceeding  from  (or  converging  in  a penis  at)  one  median  point,  repre- 
sent two  segmental  organs,  united  at  the  mid-hne  and  modified  into  this  special  system 
of  parts.  But  all  this  is  accomplished,  not  by  the  introduction  of  a new  structure  or 
glandular  appendages  called  ovaries.  De  Quatbeeages  thus  adopts  and  confirms  the  account  given  many 
years  before  by  Dxjges  of  the  female  system  of  Hirudo  officinalis.  The  male  system  in  Hirudo  vacca  is 
correctly  described  by  De  Quatbeeages.  The  true  feminine  organs  he  has  completely  overlooked.  The 
same  charge  is  to  be  preferred  against  this  anatomist  with  reference  to  the  descriptions  given  by  him  of  the 
reproductive  organs  of  Hirudo  hranchiata  (see  his  “Memoire  sur  le  BrancheUion  de  D’Obbignx,”  Annal. 
d.  Sc.  Nat.  1852).  He  observes:  “Les  organes  genitaux  femeUes  sont  d’une  extreme  simpHcite.  Ils  con- 
sistent en  deux  longues  poehes  renjlees  en  masse,  dont  les  canaux  excreteurs  se  renflent  legerement  vers  le 
tiers  posterieur  de  leur  trajet,  et  se  reunissent  en  un  seul  sur  la  ligne  mediane  vers  le  milieu  de  I’inter- 
valle  qui  separe  le  septieme  et  le  huitieme  ganglion.”  Thus  is  described  by  De  Quatbeeages  the  female 
system  of  this  leech.  He  here  evidently  mistakes  the  median  copulative  pouches  for  ovaria,  between  which 
and  the  latter  there  is  nothing  in  common.  In  the  same  volume  of  the  ‘ Annales  de  Sciences  NatureUes,’ 
De  Quatbeeages  figures  and  describes  the  reproductive  organs  of  Alhione  muricata.  In  this  instance  this 
author  has  not  only  altogether  overlooked  the  real  ovarian  organs,  but  the  true  testicular  series  has  also 
altogether  eluded  his  observation ! 
* In  my  Eeport  on  the  Annelids,  1851, 1 was  led  to  the  mistake  of  believing  that  each  ovary  communicates 
directly  with  each  testis  by  means  of  a duct,  thus  permitting  of  an  internal  impregnation  of  the  ova.  This 
duct  is  however,  I am  now  convinced,  as  Professor  Owen  (see  last  edition  of  his  Lectures  on  the  Inverte- 
brata,  1.855)  has  pointed  out,  a branch  from  the  median  vessel  which  goes  to  supply  the  segmental  organ. 
MDCCCLVIII.  R 
