THE  ORNITHORHYNCHUS  PARADOXUS. 
239 
stem  of  grass,  not  much  larger  in  diameter  than  a  hog's  bristle,  to  pass  through  it ;  just 
within  the  orifice  were  two  small  raised  reddish  bodies,  the  use  of  which  I  do  not  know\ 
The  interior  coats  of  the  uterus  were  corrugated  and  of  a  fine  pinkish  colour. 
On  laying  open  the  right  uterus,  although  it  was  also  enlarged  and  had  some  degree 
of  vascularity,  with  ovaries  on  its  upper  part,  no  eggs  were  found  within  :  internally 
it  had  the  same  corrugated  appearance  as  was  observed  in  the  left,  but  the  vascular 
tinge  existed  in  a  less  degree. 
The  cheek-pouches,  or,  as  I  am  inclined  to  consider  them,  the  first  stomachs,  of  both 
stratum :  but  the  theca,  or  innermost  parietes  of  the  sac,  was  much  thickened,  and  encroached  irregularly  upon 
the  empty  space,  so  as  to  leave  only  a  cylindrical  passage  to  the  external  opening.  *  *  *  * 
"  The  two  smallest  sized  ova  *  *  *  were  situated  at  the  upper  part  of  the  left  uterus,  and  at  the  distance  of 
about  a  line  from  each  other.  Each  ovum  was  spherical  in  form,  and  measured  two  lines  and  a  half  in  diameter  : 
they  were  of  a  deep  yellow  colour,  with  a  smooth  and  polished  surface,  and  had  not  the  slightest  adherence  to 
the  uterine  parietes. 
"  The  two  ova  next  in  size  *  *  *  measured  each  three  lines  in  diameter,  and  were  situated  a  little  below  the 
middle  of  the  left  uterus  :  they  were  of  a  spherical  form,  but  had  evidently  been  slightly  compressed  in  the  uterine 
ca\'ity.  They  were  of  a  lighter  colour  than  the  preceding,  a  circumstance  which  was  specially  evident  at  the 
upper  part,  from  the  subsidence  of  the  contained  vitelline  mass.  Externally  they  were  smooth,  and  rolled 
freely  out  of  the  position  where  they  were  lodged  like  those  of  the  preceding  specimen. 
"  The  largest  ovum  *  *  *  had  the  same  spherical  form,  smooth  exterior  surface,  and  freedom  from  connexion 
with  the  uterus,  as  the  preceding,  but  was  of  a  much  lighter  colour,  owing  to  the  increased  quantity  of  its  fluid 
contents,  to  which  its  greater  size  was  chiefly  attributable.  It  measured  three  lines  and  a  half  in  diameter, 
and  had  been  situated  in  a  depression  or  cell  a  little  below  the  middle  of  the  left  uterus.  The  lining  membrane 
of  the  uterus  was  highly  vascular  in  the  recent  state  in  each  of  the  above  specimens. 
"  In  all  these  ova  the  contents  could  be  seen,  through  the  cortical  or  outer  membrane,  to  be  of  two  kinds, 
viz.,  a  greyish  subtransparent  fluid  and  a  yellowish  denser  mass,  which  varied  in  their  relative  proportions  as 
above  mentioned,  the  denser  substance  always  subsiding  to  the  lowest  part  of  the  ovum,  whichever  way  it  was 
turned.  In  the  largest  ovum,  the  yellow  naass  or  yolk  occupied  about  one  third  of  its  cavity,  while  in  the  small- 
est it  constituted  four  fifths  of  the  whole  mass. 
"  The  chorion  or  cortical  membrane  of  these  ova  offered  a  moderate  degree  of  resistance  when  torn  open  with 
the  forceps,  and  yielded  equally  in  every  direction  when  separated  from  the  yolk,  the  rent  margins  curling  in- 
wards like  the  coats  of  a  hydatid.  This  membrane  was  of  a  dull  greyish  colour  inclining  to  brown,  slightly  trans- 
parent, and  more  polished  upon  its  inner  than  upon  its  outer  surface  :  it  resembles  the  cortical  membrane  of 
the  ovum  of  the  Salamander,  but  is  of  a  more  delicate  texture.  The  fluid  contents  occupied  the  space  between 
the  cortical  and  vitelline  membranes,  a  situation  analogous  to  that  of  the  albumen  in  the  egg  of  the  Fowl, 
but  had  not  become  coagulated  by  the  action  of  the  spirit  in  which  the  ova  had  been  so  long  immersed. 
"  The  yellow  matter,  or  yolk,  was  seen  to  be  invested  by  its  proper  capsule,  which,  when  reflected  under 
the  microscope,  was  found  to  consist  of  an  extremely  thin,  smooth,  and  transparent  outer  layer,  which  I  regard 
as  the  mernhrana  vitelli,  with  a  thicker  granular  membrane  immediately  lining  it,  analogous  to  the  blastoderma 
or  germinative  membrane.  The  contents  of  the  above  investments,  or  substance  of  the  yolk,  consisted  of  innu- 
merable minute  opake  granules,  similar  in  size  and  regularity  of  form  to  those  contained  In  the  ovarian  follicles, 
and  with  these  granules  were  mingled  larger  transparent  globules  of  oil.  There  was  not  the  slightest  trace  of 
chalazce  attached  to  the  vitelline  membrane,  as,  from  analogy,  we  should  expect  to  be  the  case  had  the  ovim 
been  destined  to  have  been  perfected  by  incubation.  I  was  unable  to  detect  any  rudiments  of  the  embryo." — 
Philosophical  Transactions  for  1834,  p.  555. 
