has  a  honeycomb  appearance.  The  cj'sts  are  filled  with  a  transparent  or
opaque  gelatinous  fluid  and  present  the  appearance  of  alveolar  colloid
cancer.  There  is  a  tendency  to  disintegrating  ulceration.  The  spleen  is
usually  enlarged.  Jaundice  is  common.  There  is  a  ten-
dency to  hemorrhage  and   the  prognosis  is  unfavorable.
D.  DISEASES  DUE  TO  NEMATODES.
Nematodes  are  elongated  round  worms  of  a  filifomi
or  fusiform  shape,  provided  with  a  mouth  and  intrstinal
apparatus.  The  sexes  are  in  most  species  separate  and
the  male  can  be  distinguished  from  the  female  by  its
smaller  and  more  slender  form  and  spiral  or  incur\-ated
posterior  extremity.  Fertilization  takes  place  within  the
uterus,  and  the  ova,  according  to  the  species,  are  deposited
before  or  during  segmentation  or  with  the  embryo  fully
developed.  A  few  species  are  viviparous.  The  mo<lc  of
infection  of  the  host  differs  according  to  the  species  of  worm.
i.  Ascariasis.
Ascaris  LumbricoldeA. — The  bo<:ly  is  spindle-shaped
and  of  a  reddish  or  grayish-yellow  color,  with  four  longi-
tudinal bands  and  transverse  markings.  The  male  meas-
ures 12-25  cm.  in  length  and  about  3  mm.  in  transverse
diameter  at  its  thickest  part;  the  female  from  20—10  cm.
by  5  mm.  The  ova  are  elliptical  with  a  thick  brownish-
red  covering.  They  measure  0.05-0.07  mm.  in  length  by
0.04-0.05  mm.  in  breadth.  They  are  deposited  before
segmentation  and  are  sometimes  present  in  the  stools  in
great  numbers.  Generation  takes  place  without  inter-
mediate host.  Thi's  nematode  worm  is  the  most  common
parasite  of  man  and  is  distributed  over  the  entire  world.
