from  the  head,  increase  in  size  until  about  10  to  15  mm.  broad  and
3  to  4  mm.  long.  The  genital  opening  is  on  the  side,  not  the  edge,
and  around  it  the  uterus  is  arranged  as  a  rosette.  The  distribution
of  these  organs  is  more  regular  than  that  of  the  septa  of  the  seg-
ments, Willson  considering  the  imperfect  or  abortive  segments  ver\'
characteristic  of  this  family  of  worms.  The  eggs  are  characteristic.
They  have  a  thin  shell,  the  contents  coarsely  granular,  mulberry-like,
and  a  lid  which  may  be  open  or  closed.  In  very  young  eggs  the
lid  cannot  be  seen,  and  in  older  may  be  rendered  evident  by  pressure


Fig.  91.— Bothriocephalus  latus.
(From  Braun.)


^  Amer.  Jour,  of  Med.  Sci.,  1902,  vol.  cxxiv.
THE   F.ECES  389

on  the  glass.  Their  size  is  70  by  45  microns.  The  eggs  are  im-
portant in  diagnosis,  since  the  segments  occur  only  at  certain  times,
although  when  they  do  occur  it  is  in  large  amounts.  The  most
interesting  thing  about  this  enormous  tape-worm  is  the  production
in  certain  of  the  hosts  of  an  anaemia  which  haematologically  cannot
be  distinguished  from  primary  pernicious  anaemia.  Only  a  small  per-
centage of  cases  which  harbor  the  worm  have  this  anaemia,  and  they
recover  rapidly  when  the  worm  is  removed.  Various  reasons  are  given
for  the  good  health  some  hosts  enjoy, — heredity,  lack  of  predisposing
causes,  etc.,  while  Dehio  thinks  the  worm  to  be  harmful  must  either
die  or  at  least  be  diseased.  The  cause  of  the  anaemia  is  pretty  cer-
tainly a  toxine  aflfecting  the  blood  and  perhaps  the  bone  marrow.
The  eggs  of  Schistosoma  h^matobium  (see  page  275)  may  also
be  found  in  the  stools.  It  is  interesting  to  note  the  number  with  the
spine  lateral  and  those  with  it  terminal.
