278  The  Natural  History  of  the  Liver-Fluke 
this  is  the  head-part,  and  at  its  tip  is  placed  the  mouth  in 
the  middle  of  a small  sucker  or  sucking-cup,  by  which  the  fluke 
can  attach  itself.  At  the  point  where  the  head  joins  the  flat 
body  and  on  the  lower  surface  is  a second  sucker — the  ventral 
sucker. 
The  liver-rot  caused  by  these  flukes  is  always  common  in 
certain  districts  of  England,  and  it  has  been  estimated  that  the 
average  annual  loss  of  sheep  in  the  United  Kingdom  amounts 
to  no  less  than  1,000,000.  The  rot  also  occurs  almost  all  over 
the  world,  extending  to  Egypt,  Australia,  Tasmania,  and  North 
and  South  America,  and  is  nearly  or  sometimes  quite  as  des- 
tructive in  these  countries  as  in  the  British  Isles.  Professor 
Leuckart  estimates  the  average  loss  per  annum  in  Central 
Europe  alone  at  1,000,000  head. 
But  a series  of  wet  seasons  always  increases  the  prevalence  of 
the  disease.  At  such  times  it  spreads  to  districts  which  are  ordi- 
narily quite  free  from  it.  The  year  1879  was  one  of  a succession 
of  wet  seasons,  and  the  losses  during  the  end  of  that  year  and 
the  following  spring  amounted  to  no  less  than  3,000,000  sheep. 
In  his  Report  to  the  ‘ Journal  of  the  Royal  Agricultural  Society  ’* 
Mr.  Finlay  Dun  estimates  that  the  same  number  of  sheep  died 
or  were  sacrificed  from  rot  during  the  following  year.  As  this 
is  equivalent  to  the  loss  during  each  year  of  about  one-tenth  of 
the  total  number  of  the  sheep  in  the  United  Kingdom,  and 
represents  the  loss  of  six  or  eight  millions  sterling  f per  annum, 
the  serious  nature  of  the  epidemic  will  be  only  too  readily  seen. 
Such  a loss  would  be  most  grievous  at  any  time,  but  was 
especially  so  at  a time  of  bad  seasons  and  wide-spread  agri- 
cultural depression. 
A portion  of  the  loss  falls  of  course  upon  the  consumer,  as  is 
shown  by  the  increase  in  the  price  of  mutton.  Furthermore,  the 
quality  of  a portion  of  the  supply  which  comes  to  the  market 
is  necessarily  poor. 
When  the  disease  had  spread  so  widely  and  had  became  so 
exceedingly  destructive,  it  was  doubly  necessary  that  we  should 
bestir  ourselves  and  try  all  possible  preventive  means. 
But  what  were  the  right  measures  of  prevention  ? Here, 
unfortunately,  was  the  great  difficulty.  Nothing  exact  had 
been  found  out  as  to  the  way  in  which  the  fluke  entered  the 
sheep,  and  we  had  to  contend  against  an  insidious  enemy  who 
was  invisible  to  us,  to  strike  blindly  and  in  the  dark. 
In  this  state  of  uncertainty  it  was  a matter  of  national 
* Second  Series,  vol.  xvii.  p.  141. 
t It  is  very  difficult  to  ascertain  the  real  loss  in  money,  as  rotten  sheep  are 
frequently  sold  for  food,  though  at  a considerable  loss.  But  in  very  many 
instances  the  animals  were  sold  merely  for  the  price  of  the  skins. 
