DISINFECTANTS  IN  ARRESTING  CATTLE  PLAGUE.  359 
proofs  which  follow.  They  have  been  corroborated  by  numerous 
small  laboratory  experiments,  as  well  as  by  practical  operations 
at  different  farm-houses. 
8.  Whether  this  theory  thus  briefly  sketched  be  adopted  or 
not,  or  whether  it  be  regarded  as  a  provisional  scientific  artifice, 
it  certainly  includes  and  explains  a  far  greater  number  of  the 
phenomena  of  pestilence  than  any  other  hitherto  propounded. 
Moreover,  it  is  the  theory  sanctioned  by  the  most  influential  of 
those  medical  philosophers  who  have  the  best  right  to  be  heard 
on  this  subject,  and  notably  by  the  distinguished  Registrar- 
General,  Dr.  Farr,  who,  by  the  adoption  of  the  word  zymotic,  in 
his  classification  of  diseases,  has  implied  his  adhesion  to  this 
theory. 
9.  Bearing  upon  the  communicability  of  this  disease  are  other 
questions,  which  hitherto  have  not  received  a  satisfactory  settle- 
ment. How  does  the  virus  travel  ?  What  amount  of  resistance 
to  ordinary  conditions  of  moisture  and  time  does  its  vitality  con- 
fer upon  it  ?  Will  it  propagate  and  multiply,  outside  the  animal 
body,  under  favorable  conditions  of  warmth  and  moisture  ?  And 
can  we  find  any  chemical  disinfectant  or  antiseptic  which  will 
readily  destroy  it  ? 
The  extreme  communicability  of  the  pestilence  may  arise 
either  from  the  eminently  diffusible  character  of  the  virus-cells, 
or  from  their  persistent  vitality,  or  from  both  conditions  com- 
bined. It  is  proved  that  the  materies  morbi  will  adhere  to  cloth- 
ing, and  can  be  carried  a  considerable  distance  in  it ;  that  the 
breath,  perspiration,  and  evacuations  of  the  diseased  animal  are 
loaded  with  virus-cells ;  and  that  the  secretions  from  the  mouth, 
nose,  and  eyes  are  in  a  similar  condition.  It  follows,  therefore, 
that  the  sheds,  in  which  diseased  animals  have  stood,  become 
impregnated  with  the  virus,  ready  to  settle  on  the  cfc)thes  of 
every  one  who  enters  ;  that  ponds,  streams,  and  even  wells  may 
become  contaminated  through  foul  soakage ;  that  a  road  over 
which  diseased  cattle  have  been  driven  may  be  poisoned  along 
its  whole  distance  by  the  evacuations  aud  other  discharges  from 
the  animals  ;  whilst  their  very  breath,  carried  by  the  Vind,  may 
plant  the  seeds  of  infection  in  all  the  healthy  farms  by  which  the 
road  passes, 
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