﻿FILTRABLE 
  VIRUSES 
  BOYCOTT 
  339 
  

  

  on 
  some 
  of 
  the 
  complexion 
  of 
  Charles 
  Creighton's 
  outlook 
  and 
  do 
  our 
  

   best 
  to 
  imitate 
  his 
  learning 
  and 
  industry. 
  

  

  The 
  chief 
  way 
  in 
  which 
  the 
  virus 
  of, 
  e. 
  g., 
  foot-and-mouth 
  disease 
  

   differs 
  from 
  the 
  Rous 
  agent, 
  and, 
  going, 
  a 
  step 
  further 
  back, 
  from 
  the 
  

   products 
  of 
  autolysis 
  (or 
  metabolism) 
  which 
  stimidate 
  growth, 
  is 
  that 
  

   it 
  seems 
  to 
  spread 
  about 
  pretty 
  easily 
  from 
  one 
  individual 
  to 
  another; 
  

   chiefly, 
  I 
  think, 
  from 
  the 
  parallel 
  of 
  bacteria 
  we 
  take 
  this 
  to 
  imply 
  

   the 
  possibility 
  of 
  independent 
  life 
  and 
  probably 
  independent 
  multi- 
  

   plication. 
  But 
  we 
  have 
  no 
  direct 
  evidence 
  of 
  this; 
  all 
  we 
  know 
  is 
  

   that, 
  like 
  the 
  Rous 
  agent, 
  it 
  can 
  be 
  deliberately 
  dispersed 
  through 
  any 
  

   number 
  of 
  individuals 
  indefinitely, 
  and 
  that 
  it 
  multiplies 
  only 
  when 
  

   and 
  where 
  it 
  produces 
  its 
  specific 
  efl^ect. 
  The 
  blister 
  which 
  is 
  deter- 
  

   mined 
  on 
  the 
  foot 
  of 
  an 
  inoculated 
  guinea 
  pig 
  by 
  slight 
  local 
  injury 
  

   is 
  preeminently 
  the 
  place 
  in 
  the 
  body 
  where 
  the 
  virus 
  is 
  found 
  in 
  the 
  

   largest 
  amount, 
  and, 
  trying 
  to 
  be 
  as 
  open-minded 
  as 
  we 
  can, 
  we 
  must 
  

   allow 
  that 
  this 
  may 
  be 
  due 
  either 
  to 
  the 
  lesion 
  being 
  produced 
  where 
  

   the 
  agent 
  is 
  present 
  in 
  greatest 
  quantity, 
  or 
  to 
  the 
  agent 
  being 
  pro- 
  

   duced 
  in 
  greatest 
  quantity 
  where 
  the 
  lesion 
  is. 
  You 
  may 
  say 
  that 
  

   if 
  the 
  guinea 
  pig 
  is 
  inoculated 
  with 
  a 
  filtrate, 
  i. 
  e., 
  with 
  nothing 
  but 
  

   virus, 
  the 
  lesion 
  must 
  be 
  due 
  to 
  the 
  virus. 
  No 
  doubt 
  that 
  is 
  in 
  a 
  

   general 
  way 
  true, 
  but 
  it 
  does 
  not 
  follow 
  that 
  the 
  whole 
  of 
  what 
  we 
  

   call 
  the 
  lesion 
  is 
  due 
  to 
  the 
  immediate 
  and 
  direct 
  action 
  of 
  the 
  virus. 
  

   Local 
  effects 
  at 
  the 
  site 
  of 
  inoculation 
  (if 
  they 
  occur) 
  prove 
  nothing; 
  

   they 
  may 
  well 
  be 
  determined 
  by 
  the 
  concomitant 
  injury. 
  Putting 
  

   aside 
  all 
  bacteriological 
  analog}'", 
  we 
  have 
  no 
  proof 
  that 
  the 
  particles 
  

   of 
  virus 
  which 
  we 
  get 
  out 
  of 
  the 
  lesion 
  are 
  directly 
  descended 
  from 
  

   those 
  we 
  put 
  in. 
  In 
  other 
  words, 
  we 
  have 
  to 
  reopen 
  the 
  question 
  

   which 
  most 
  of 
  us 
  regard 
  as 
  settled 
  : 
  Is 
  the 
  agent 
  the 
  cause 
  of 
  the 
  disease 
  

   or 
  is 
  the 
  disease 
  the 
  cause 
  of 
  the 
  agent? 
  Another 
  stupid 
  antithesis, 
  

   for 
  the 
  alternatives 
  are 
  not 
  mutually 
  exclusive; 
  both 
  might 
  be 
  true. 
  

  

  From 
  the 
  time 
  when 
  Pasteur 
  first 
  began 
  to 
  persuade 
  the 
  world 
  thai 
  

   microorganisms 
  might 
  be 
  something 
  more 
  important 
  and 
  effective 
  

   than 
  microscopical 
  curiosities, 
  there 
  have 
  never 
  been 
  wanting 
  noncon- 
  

   formists 
  who 
  have 
  held 
  that 
  microbes 
  were 
  the 
  result 
  rather 
  than 
  the 
  

   cause 
  of 
  putrefaction, 
  fermentation, 
  and 
  disease. 
  It 
  is 
  very 
  diffi- 
  

   cult 
  — 
  indeed, 
  it 
  seems 
  impossible 
  — 
  to 
  believe 
  in 
  this 
  thesis 
  in 
  respect 
  of 
  

   bacteria 
  which 
  can 
  be 
  shown 
  to 
  have 
  an 
  independent 
  life 
  by 
  cultivation 
  

   and 
  which 
  can 
  be 
  inoculated 
  into 
  an 
  animal 
  with 
  the 
  production 
  of 
  a 
  

   definite 
  disease 
  (e. 
  g., 
  tuberculosis); 
  the 
  bacteria 
  which 
  we 
  get 
  out 
  of 
  

   the 
  experimental 
  lesion 
  may 
  without 
  undue 
  credulity 
  be 
  supposed 
  to 
  

   be 
  the 
  direct 
  descendants 
  of 
  those 
  wliich 
  we 
  have 
  put 
  in 
  to 
  produce 
  it. 
  

   But, 
  as 
  Hamer 
  and 
  Crookshank 
  remind 
  us, 
  we 
  have 
  quite 
  possibly 
  

   gone 
  too 
  far 
  in 
  identifying 
  a 
  "disease" 
  with 
  its 
  accompanying 
  microbe 
  

   and 
  'defining 
  diseases 
  in 
  terms 
  of 
  what 
  we 
  believe 
  to 
  be 
  their 
  causative 
  

   agents. 
  If 
  it 
  is 
  sound 
  to 
  do 
  this 
  (as 
  it 
  'certainly 
  appears 
  to 
  be) 
  with 
  

   82322—30 
  23 
  

  

  