298  The  Natural  History  of  the  Liver-Fluke 
chances,  and  must  begin  the  prevention  of  rot  by  waging  a war 
of  extermination  against  the  eggs.  If  we  can  destroy  or, 
better  still,  render  impossible  the  production  of  nine  out  of  every 
ten  fluke-eggs  which  are  annually  scattered  in  England,  we  shall 
so  mitigate  the  rot,  that  instead  of  a sheep  being  infested  with 
two  or  three  hundred  flukes,  it  will  on  the  average  contain  only 
twenty  or  thirty.  Now  whilst  two  or  three  hundred  flukes 
would  destroy  a sheep,  twenty  or  thirty  will  do  comparatively 
little  harm. 
The  production  of  fluke-eggs  may  of  course  be  prevented  by 
killing  the  sheep  as  soon  as  it  is  known  that  it  is  suffering  from 
the  rot.  Extreme  as  this  measure  may  seem  to  some,  if  the 
sheep  are  at  all  badly  rotted  it  will  prove  the  most  economical 
in  the  end,  especially  if  the  disease  is  discovered  at  an  early 
stage.  It  is  better  to  lose  a little  at  the  outset  than  to  run  the 
risk  of  having  finally  to  sell  the  sheep  for  little  more  than  the 
price  of  the  skin.  The  quality  of  the  meat  will  be  only  slightly 
deteriorated  at  first,  and  there  will  then  be  no  objection  to  its 
use  for  food.  But  as  the  disease  advances,  the  meat  will  become 
less  and  less  wholesome,  and  at  last  become  totally  unfit  for 
human  consumption. 
There  is  no  cure  known  for  the  rot,  for  the  fluke  inhabits  the 
liver,  an  organ  which  can  only  be  reached  through  the  blood, 
and  it  is  impossible  to  prescribe  any  drug  which  will  harm 
the  fluke  without  harming  the  sheep  at  the  same  time.  It  is 
quite  true  that  if  the  sheep  does  not  contain  too  many  flukes,  it 
may  recover  when  the  natural  life  of  the  fluke  comes  to  an  end, 
provided  its  strength  is  kept  up  by  a liberal  diet.  But  the  life  of 
the  fluke  may  last  so  long  (see  pp.  294-5),  that  even  if  this 
method  prove  successful,  it  will  be  very  costly,  and  it  is  scarcely 
worth  while  making  the  attempt,  unless  the  sheep  be  of  a 
specially  valuable  breed,  or  unless  there  is  reason  to  believe  that 
it  contains  only  a small  number  of  flukes.  If  the  owner  decides 
to  try  to  keep  the  infected  flocks,  they  should  not  be  allowed 
to  remain  on  wet  ground,  for  then  the  fluke-eggs  would  have  a 
favourable  place  for  hatching,  and  the  result  might  be  a harvest 
of  death  reaped  in  the  following  season. 
If  rotten  sheep  are  kept  at  all,  let  them  be  placed  on  dry 
ground,  where  the  eggs  cannot  meet  with  the  moisture  neces- 
sary for  their  development,  and  where  there  is  no  chance  of 
their  being  washed  into  ditches,  ponds,  or  streams.  A brook 
may  easily  carry  the  eggs  down  with  its  current  to  land  lying  at  a 
lower  level. 
If  there  is  reason  to  suspect  that  a flock  of  sheep  is  attacked 
with  liver- rot,  either  one  of  the  most  suspicious-looking  should 
be  killed,  and  its  liver  examined  for  flukes  ; or  if  a microscope 
