﻿FILTEABLE 
  VIRUSES 
  BOYCOTT 
  341 
  

  

  I 
  daresay, 
  however, 
  that 
  some 
  simple 
  explanation 
  will 
  be 
  found 
  

   for 
  these 
  epidemiological 
  difficulties 
  and 
  that 
  any 
  suspicions 
  that 
  

   we 
  may 
  have 
  about 
  the 
  origin 
  of 
  these 
  viruses 
  will 
  be 
  allaj^ed. 
  Viruses 
  

   can 
  remain 
  dormant 
  in 
  live 
  animals 
  for 
  a 
  long 
  time 
  and 
  carriers 
  might 
  

   be 
  activated 
  by 
  a 
  variety 
  of 
  incidents. 
  But 
  what 
  are 
  we 
  to 
  make 
  

   of 
  such 
  a 
  phenomenon 
  as 
  Virus 
  III? 
  Virus 
  III 
  is 
  made 
  manifest 
  

   by 
  inoculating 
  a 
  filtrate 
  of 
  an 
  emulsion 
  of 
  a 
  rabbit's 
  testis 
  into 
  the 
  

   testis 
  of 
  another 
  rabbit. 
  Th^s 
  procedure 
  is 
  sometimes 
  followed 
  by 
  

   an 
  inflammatory 
  reaction 
  and 
  the 
  production 
  of 
  intranuclear 
  "bodies," 
  

   and 
  if 
  this 
  inflamed 
  testis 
  is 
  emulsified 
  and 
  the 
  filtrate 
  inoculated 
  

   into 
  another 
  fresh 
  rabbit 
  the 
  inflammatory 
  condition 
  is 
  reproduced; 
  

   thereafter 
  the 
  "disease" 
  can 
  be 
  carried 
  on 
  indefinitely. 
  It 
  is 
  not 
  

   fatal, 
  and 
  after 
  his 
  attack 
  has 
  subsided 
  a 
  rabbit 
  is 
  refractory 
  to 
  

   further 
  inoculations 
  and 
  his 
  blood 
  serum 
  can 
  prevent 
  infection 
  with 
  

   active 
  virus. 
  If 
  we 
  knew 
  nothing 
  of 
  bacteriology, 
  should 
  we 
  not 
  

   conclude 
  that 
  the 
  virus 
  had 
  been 
  generated 
  by 
  our 
  procedures 
  from 
  

   the 
  tissues 
  of 
  the 
  normal 
  testis? 
  The 
  only 
  evidence 
  to 
  the 
  contrary 
  

   is 
  analogy, 
  and 
  the 
  slender 
  fact 
  that 
  the 
  phenomenon 
  comes 
  off 
  

   more 
  easily 
  in 
  New 
  York 
  than 
  in 
  London 
  rabbits. 
  I 
  do 
  not 
  know 
  

   how 
  many 
  people 
  have 
  tried 
  similar 
  experiments 
  with 
  other 
  appar- 
  

   ently 
  normal 
  tissues; 
  if 
  they 
  had 
  been 
  positive 
  we 
  should 
  certainly 
  

   have 
  heard 
  about 
  them; 
  Leitch's, 
  Brebner's, 
  and 
  Murphy's 
  successes 
  

   with 
  sarcoma 
  have 
  already 
  been 
  mentioned, 
  and 
  bacteriolysins 
  

   transmissible 
  in 
  series 
  have 
  been 
  extracted 
  from 
  normal 
  organs. 
  

  

  It 
  might 
  be 
  expected 
  that 
  what 
  we 
  know 
  of 
  immunity 
  to 
  these 
  

   vu-uses 
  would 
  throw 
  some 
  light 
  on 
  their 
  origin 
  and 
  nature, 
  but 
  as 
  a 
  

   matter 
  of 
  fact 
  it 
  does 
  not 
  seem 
  to 
  give 
  us 
  much 
  help; 
  as 
  far 
  as 
  it 
  goes, 
  

   it 
  is 
  perhaps 
  against 
  their 
  autochthonous 
  origin. 
  Two 
  points 
  are 
  

   certainly 
  clear. 
  In 
  susceptibility 
  to 
  reinoculation 
  and 
  in 
  the 
  neutral- 
  

   izing 
  properties 
  of 
  the 
  blood-serum, 
  the 
  immune 
  reactions 
  are 
  at 
  

   least 
  as 
  sharply 
  specific 
  as 
  they 
  are 
  with 
  most 
  bacteria; 
  some 
  viruses 
  

   show 
  immunological 
  races 
  as 
  bacteria 
  do. 
  The 
  facts 
  of 
  natural 
  

   immunity 
  are 
  also 
  very 
  similar; 
  a 
  virus 
  may 
  affect 
  one, 
  two, 
  or 
  several 
  

   species 
  of 
  host 
  and 
  have 
  special 
  affinities 
  for 
  certain 
  tissues. 
  We 
  

   might 
  use 
  this 
  analogy, 
  and 
  the 
  general 
  proposition 
  that 
  immune 
  

   reactions 
  occur 
  only 
  if 
  the 
  antigen 
  and 
  the 
  reacting 
  animal 
  are 
  of 
  

   different 
  species, 
  to 
  argue 
  that 
  viruses 
  must 
  come 
  from 
  outside 
  the 
  

   affected 
  animal, 
  and 
  to 
  say, 
  e. 
  g., 
  that 
  if 
  virus 
  III 
  originates 
  from 
  

   rabbit 
  tissues 
  it 
  ought 
  not 
  to 
  stimulate 
  a 
  rabbit 
  to 
  an 
  antiresponse 
  

   as 
  it 
  does. 
  The 
  argument 
  seems 
  to 
  be 
  rather 
  a 
  strong 
  one, 
  but 
  it 
  

   is 
  not 
  conclusive. 
  It 
  is 
  easy 
  to 
  suppose 
  that 
  the 
  virus, 
  whatever 
  

   its 
  origin, 
  would 
  not 
  have 
  on 
  it 
  the 
  stamp 
  of 
  complete 
  rabbitness; 
  

   considering 
  its 
  size 
  and 
  its 
  other 
  peculiarities 
  it 
  would 
  perhaps 
  be 
  

   rather 
  remarkable 
  if 
  it 
  had. 
  We 
  know, 
  too, 
  now 
  that 
  the 
  general 
  

   immunological 
  rule 
  about 
  specific 
  differences 
  and 
  specific 
  identities 
  

  

  