296  Annual  Report  for  1910  of  Royal  Veterinary  College. 
cattle  under  the  Diseases  of  Animals  Acts,  in  view  of  the 
ascertained  facts  concerning  the  pathology  of  the  disease  and 
the  information  laid  before  the  Committee  by  representatives 
of  cattle  breeding  and  dairying  in  Great  Britain. 
The  principal  facts  determined  by  the  Committee  concerning 
the  causation  of  the  disease  may  be  summarised  as  follows. 
The  common,  if  not  the  exclusive,  cause  of  multiple  cases 
of  abortion  occurring  in  the  same  herd  in  Great  Britain  is  a 
very  minute  bacillus — the  bacillus  of  cattle  abortion.  This 
organism  is  identical  with  the  one  which  Professor  Bang  had 
previously  proved  to  be  the  cause  of  epizootic  abortion  of  cattle 
in  Denmark. 
The  organism  in  question  has  very  distinctive  characters, 
both  in  respect  of  its  morphology  and  the  appearance  pre- 
sented by  its  cultures  in  artificial  media.  By  these  characters 
it  can  be  distinguished  from  any  other  organism  at  present 
known  to  bacteriologists.  Unlike  many  other  bacteria,  it  is 
not  very  easily  cultivated  outside  the  body,  and  this  fact  lends 
strong  support  to  the  view  that  in  nature  it  never  multiplies 
except  in  infected  animals.  Although  multiple  cases  of  abor- 
tion occur  in  other  species  than  the  bovine  one,  the  organism 
in  question  has  never  been  encountered  in  any  other  animals 
except  pregnant  cows.  Experiments  conducted  by  the  Com- 
mittee showed  that  the  organism  has  a wide  range  of  pathogenic 
power  and  is  capable  of  causing  abortion  when  experimentally 
introduced  into  pregnant  animals  belonging  to  several  different 
species,  but  there  is  at  present  no  evidence  to  show  that  in 
natural  cases  it  ever  is  the  cause  of  abortion  in  other  animals 
than  cows. 
Although  the  disease  for  which  the  organism  is  responsible 
is  termed  epizootic  abortion,  the  real  disease  is  au  inflammation 
of  the  pregnant  womb  and  of  the  membranes  which  surround 
the  foetus  ; and  the  act  of  abortion,  when  it  occurs,  is  merely 
a symptom  of  this  inflammation  of  the  womb.  In  infected 
cows  killed  before  the  act  of  abortion  the  bacillus  is  usually 
found  in  immense  numbers,  chiefly  between  the  womb  and 
foetal  membranes,  but  in  a considerable  proportion  of  cases  it 
is  also  present  in  small  numbers  in  the  body  of  the  foetus  itself, 
and  especially  in  the  stomach  contents. 
It  was  at  one  time  very  generally  believed  that  the  common 
method  by  which  the  disease  was  naturally  spread  was  the 
introduction  into  the  genital  passages  of  the  cow  of  infective 
material  which  had  escaped  from  a previously  affected  animal, 
such  introduction  usually  taking  place  by  contact  of  the  hind 
parts  of  the  cow  with  the  contaminated  floor  of  a cow-shed. 
The  Committee  found  that  the  most  certain  method  of  experi- 
mental infection  was  the  direct  injection  of  bacilli  into  the 
