356        DISINFECTANTS  IN  ARRESTING  CATTLE  PLAGUE. 
ON  THE  APPLICATION  OF  DISINFECTANTS  IN  ARREST- 
ING THE  SPREAD  OF  THE  CATTLE  PLAGUE. 
Report  to  Her  Majesty's  Commissioners, 
By  William  Crookes,  F.  R.  S. 
Part  I.-— Theoretical  Considerations  as  to  the  Propagation  of 
the  Cattle  Plague. 
1.  Previous  to  my  receiving  instructions  from  the  Royal  Com- 
mission for  inquiring  into  the  origin  and  nature  of  the  cattle 
plague,  I  had  devoted  considerable  attention  to  the  investigation 
of  the  applicability  of  disinfectants  to  the  prevention  or  cure  of 
this  pestilence,  ever  since  its  first  appearance  in  England,  and 
had  tried  numerous  experiments  both  in  the  laboratory  and  also 
on  a  large  scale  in  farm-yards.  I  was  therefore  not  unprepared 
to  commence  at  once  the  practical  operations  which  it  was  con- 
sidered desirable  to  carry  out. 
2.  As  to  the  bare  fact  of  the  infectious*  nature  of  the  cattle 
plague  all  are  agreed.  That  contamination  of  some  kind  is  com- 
municated from  a  diseased  to  a  healthy  animal  is  obvious  to 
every  one ;  but  when  we  inquire  by  what  agency  the  disease  is 
carried,  the  answers  are  of  the  most  conflicting  kind.  Some- 
thing, evidently  a  material  substance,  passes  from  one  beast  to 
another  ;  but  what  is  this  something  ?  Is  it  a  solid,  a  liquid,  or 
a  gas ;  living  or  dead ;  an  animal  or  a  vegetable  germ  ;  a  poison, 
virus  or  ferment  ?  Each  of  these  views  has  found  advocates,  and 
in  favor  of  each  something  may  be  said. 
3.  There  are  weighty  reasons  for  deciding  that  the  infecting 
matter  is  neither  a  gas  nor  even  a  volatile  liquid.  The  almost 
infinite  attenuation  which  a  gas  undergoes  owing  to  its  rapid 
diffusion  into  the  atmosphere,  would  render  its  supposed  noxious 
influence  imperceptible  a  few  yards  from  the  focus  of  infection. 
Moreover,  the  infection  is  capable  of  being  carried  considerable 
*  I  have  throughout  this  Report  used  the  word  "  infectious  "  in  prefer- 
ence to  "  contagious."  The  limitation  to  actual  contact  involved  in  the 
word  contagious,  and  the  popular  opinions  which  the  use  of  these  words 
foster,  that  some  diseases  are  infectious  and  not  contagions,  whilst  others 
may  be  contagious  though  not  infectious,  imply  a  far  more  profound 
knowledge  of  the  way  in  which  diseases  are  transmitted  than  we  yet  pos- 
sess. I  therefore  prefer  the  wider  term  infectious,  as  being  more  applica- 
ble to  our  present  knowledge  on  the  subject. 
