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MR.  G.  BENNETT  ON  THE  HISTORY  AND  HABITS  OF 
was  afterwards  confirmed  by  facts,)  that  as  the  gestation  advances,  the  gland  becomes 
enlarged ;  and  that  when  the  lacteal  secretion  is  no  longer  required  for  the  support  of 
the  young,  it  again  decreases,  becoming  scarcely  perceptible. 
Omitting  the  rest  of  the  anatomy,  I  shall  at  once  proceed  to  the  result  of  the  inves- 
tigation of  the  uterine  organs.  These  I  found  to  consist  of  two  uteri  extending  some 
distance  above  the  pelvis.  On  the  upper,  rather  posterior  and  lateral  part  of  the  uteri 
(but  more  particularly  and  more  clearly  marked  in  the  left  than  in  the  right  uterus,)  were 
well  developed  clusters  of  ova,  giving  an  indication  of  an  impregnated  female.  Both 
uteri,  gradually  diminishing  in  size  as  they  proceeded,  had  their  termination  in  the 
cloaca ;  the  bladder  was  situated  between  and  rather  anterior  to  the  uteri,  and  the  rectum 
posterior  to  the  bladder  ;  and  both  these  organs  also  had  their  termination  in  the  cloaca. 
The  ovaries  were  white',  and  covered  by  a  semitransparent  membrane,  through  which 
the  ova  could  be  readily  distinguished.  The  left  uterus  had  the  largest  development : 
its  coats  were  thickened,  and  on  laying  the  internal  part  open  gradually  from  the  os 
uteri  to  the  apex,  three  loose  ova  of  the  size  of  swan-shot  were  successively  exposed  to 
view,  one  a  short  distance  above  the  other,  but  all  in  the  uterine  cavity.  They  were 
perfectly  white  and  quite  round ;  their  external  coat  consisted  of  a  dense  opake  mem- 
brane ;  and  they  could  be  taken  into  the  hand  and  examined  without  fear  of  their  sus- 
taining any  injury^. 
The  OS  uteri  was  contracted  so  closely  at  this  period  as  scarcely  to  permit  a  very  thin 
'  After  having  been  preserved  in  spirits,  they  became  rather  of  a  yellowish  colour  :  indeed  the  whole  of  the 
preparation  of  the  uterine  organs  had,  as  may  be  supposed,  a  far  more  beautiful  appearance  when  viewed  in 
the  recent  state  than  after  it  had  been  for  some  time  preserved  in  spirit.  For  such  purposes  I  should  prefer 
brine  to  spirit,  as  the  natural  appearance  of  animal  preparations  is  not  so  liable  to  be  lost. 
^  I  took  the  earliest  opportunity  of  transmitting  to  my  friend  Mr.  Owen  the  impregnated  uterus  of  this  Or- 
nithorhynchus,  and  of  two  others  which  I  subsequently  obtained,  and  the  following  is  the  result  of  his  exami- 
nation of  these  specimens  as  detailed  in  a  paper  just  published  by  him  in  the  '  Philosophical  Transactions.' 
"  In  each  of  the  specimens,  the  left  ovary  only  had  taken  on  the  sexual  actions,  but  did  not  exceed  in  size  the 
same  parts  in  the  unimpregnated  specimens  above  described.  The  right  ovary  had,  however,  become  enlarged ; 
it  measured  half  an  inch  in  length,  a  third  of  an  inch  in  breadth,  and  was  about  half  a  line  in  thickness:  a  few 
ovisacs,  about  the  size  of  a  small  pin's  head,  projected  from  the  surface. 
"  The  left  ovary  in  each  of  the  specimens  was  concealed  by  the  thin  membrane  forming  the  expanded  orifice  of 
the  oviduct.  In  one  of  these  it  was  with  some  difficulty  it  could  be  withdrawn  from  the  Fallopian  aperture,  owing 
to  the  adhesion  which  was  occasioned  by  what  appeared  to  be  a  coagulated  secretion ;  a  circumstance  which 
must  have  effectually  ensured  the  passage  of  the  ovum  into  the  oviduct.  In  two  of  the  specimens,  the  left  ovary 
presented  two  empty  ovisacs,  or  corpora  lutea,  corresponding  with  the  number  of  ova  found  in  the  uterus.  In 
the  third  specimen,  the  left  ovary  presented  two  ovisacs  still  uncicatrized,  but  only  one  ovum  was  contained  in 
the  uterus.  *  *  *  * 
"  Tlie  discharged  ovisacs  were  of  an  elongated  flask-shaped  form,  about  three  lines  in  length  and  two  La 
diameter,  with  the  margins  of  the  orifice  through  which  the  ovum  and  granular  substance  had  passed  everted, 
with  a  slight  contraction,  resembling  the  neck  of  a  flask,  below  the  aperture.  On  compressing  these  ovisacs, 
small  portions  of  coagulated  substance  escaped.  When  longitudinally  divided,  they  were  found  to  consist  of 
the  same  parts  as  the  ovisac  before  impregnation,  with  the  exception  of  the  granular  contents  and  granular 
