and  the  Prevention  of  Rot. 
281 
than  water,  so  that  if  the  vessel  is  allowed  to  stand  for  an  hour 
or  two  all  the  eggs  will  fall  to  the  bottom,  and  leave  the  water 
colourless. 
The  number  of  eggs  produced  by  each  fluke  is  very  large, 
and  its  fertility  has  been  underrated.  In  one  case  I obtained 
7,000,000  eggs  from  the  gall-bladder  of  a single  sheep  suffering 
from  the  rot,  and  as  the  liver  contained  about  200  flukes,  this 
gives  an  average  of  37,000  eggs  to  each  fluke.  And  these  eggs 
were  found  in  the  gall-bladder  alone;  the  liver  must  have 
contained  at  least  as  many  more,  and  eggs  had  been  passed 
copiously  by  the  sheep  for  many  months.  The  number  of 
eggs  produced  by  a single  fluke  may  be  safely  estimated  at 
half  a million,  a number  more  easily  spoken  of  than  realised. 
It  is  very  important  that  we  should  know  more  about  the 
egg , for  it  forms  the  starting-point  of  new  generations.  But 
to  know  more  about  the  egg,  it  is  necessary  to  see  it  highly 
magnified  by  means  of  the  microscope.  Figure  1 shows  an  egg 
thus  seen.  It  is  an  oval  body,  with  a transparent  shell,  which 
allows  the  contents  to  be  distinguished.  One  end  is  a little 
rounder  and  blunter  than  the  other,  and  shows  a line  marking 
off  a rounded  portion  which  forms  a lid  to  the  rest  of  the  shell. 
A little  below  the  lid  is  a small  round  mass,  which  is  the 
present  condition  of  the  first  generation  or  animal  which  will 
ultimately  be  developed  from  the  egg.  The  remaining  contents 
of  the  egg  are  simply  a store  of  food  for  the  benefit  of  this 
animal. 
Fig.  1. 
t'gg  of  the  Liver-fluke  examined  shortly  after  it  was  taken  from  the  liver  of  a sheep.  At  the  right- 
hand  end  of  the  shell  may  be  seen  the  line  marking  off  the  lid,  and  a little  to  the  left,  the 
embryo  in  a very  early  stage  of  development.  The  embryo  is  surrounded  by  round  masses 
which  serve  as  food:  they  are  all  of  them  granular,  but  only  three  at  the  left  hand  side  have 
been  fully  drawn.  Magnified  680  times.  (Original.— A.  P.  T.) 
So  long  as  the  egg  remains  within  the  body  of  the  sheep  no 
further  change  takes  place. 
