﻿CoMMISSIO>-ER 
  OF 
  AGRICULTURE. 
  ' 
  535 
  

  

  narily 
  employed. 
  Tuberculin 
  has 
  been 
  made 
  from 
  the 
  bovine 
  

   bacillus 
  in 
  a 
  number 
  of 
  laboratories, 
  and 
  I 
  am 
  told 
  that 
  no 
  dif- 
  

   ference 
  could 
  be 
  detected 
  between 
  it 
  and 
  that 
  made 
  from 
  the 
  

   sputum 
  bacillus, 
  in 
  its 
  efficiency. 
  My 
  limited 
  experiments 
  con- 
  

   firm 
  these 
  statements, 
  although 
  the 
  bovine 
  cultures, 
  with 
  which 
  I 
  

   have 
  worked, 
  gi-ew 
  more 
  slowly 
  and 
  consequently 
  required 
  a 
  

   longer 
  period 
  of 
  incubation 
  to 
  produce 
  a 
  tuberculin 
  of 
  the 
  same 
  

   degree 
  of 
  potency. 
  

  

  Tuberculin 
  in 
  the 
  dose 
  necessary 
  to 
  bring 
  out 
  its 
  diagnostic 
  

   effects 
  is 
  absolutely 
  harmless 
  to 
  a 
  healthy 
  animal. 
  Thousands 
  

   of 
  observations 
  which 
  have 
  been 
  reported 
  assure 
  us 
  of 
  this 
  fact. 
  

  

  Tuberculin 
  is 
  in 
  dailv 
  use 
  in 
  everv 
  State 
  in 
  the 
  Union, 
  in 
  

   Canada, 
  and 
  in 
  every 
  country 
  in 
  Europe, 
  yet, 
  so 
  far 
  as 
  I 
  can 
  learn, 
  

   not 
  a 
  single 
  case 
  of 
  injury 
  following 
  its 
  use 
  in 
  healthy 
  cattle 
  has 
  

   been 
  reported. 
  Cases 
  of 
  septic 
  infection 
  following 
  its 
  use 
  must 
  

   be 
  attributed 
  to 
  other 
  causes. 
  In 
  tuberculous 
  animals 
  it 
  produces 
  

   a 
  rise 
  of 
  temperature, 
  which 
  within 
  certain 
  limits 
  follows 
  a 
  defi- 
  

   nite 
  course, 
  usually 
  terminating 
  in 
  from 
  eighteen 
  to 
  twenty-four 
  

   hours 
  after 
  the 
  injection. 
  The 
  temperature 
  usually 
  begins 
  to 
  

   rise 
  in 
  about 
  eight 
  hours, 
  giving 
  a 
  steady 
  but 
  quite 
  rapid 
  eleva- 
  

   tion 
  for 
  from 
  one 
  to 
  three 
  hours, 
  a 
  continuous 
  high 
  elevation 
  of 
  

   from 
  four 
  to 
  twelve 
  hours, 
  and 
  a 
  gradual 
  decline. 
  This 
  is 
  practi- 
  

   cally 
  constant, 
  be 
  the 
  rise 
  moderate 
  or 
  extreme. 
  In 
  addition 
  to 
  

   the 
  elevation 
  of 
  the 
  temperature 
  there 
  is 
  sometimes 
  a 
  marked 
  

   nervous 
  chill. 
  Why 
  we 
  get 
  this 
  reaction^*^ 
  is 
  not 
  positively 
  deter- 
  

   mined, 
  and 
  we 
  need 
  much 
  more 
  information 
  upon 
  this 
  subject. 
  

  

  lOTrudeau 
  (John 
  Hopkins 
  Hospital 
  Bulletin, 
  July, 
  1899) 
  gives 
  the 
  follow- 
  

   ing 
  summary 
  "of 
  the 
  mechanism 
  of 
  the 
  tuberculin 
  reaction: 
  "The 
  most 
  gen- 
  

   erally 
  accepted 
  theory 
  at 
  present 
  in 
  regard 
  to 
  it 
  is, 
  briefly, 
  the 
  small 
  dose 
  of 
  

   tuberculin 
  injected 
  is 
  a 
  partly 
  specific 
  irritant 
  both 
  to 
  tuberculous 
  foci 
  and 
  

   to 
  the 
  susceptible 
  organism 
  in 
  general. 
  It 
  produces 
  intense 
  hyperremia 
  of 
  all 
  

   tuberculous 
  tissue 
  in 
  the 
  body 
  (local 
  reaction), 
  and 
  as 
  the 
  result 
  of 
  this 
  hy- 
  

   persemia 
  much 
  toxin 
  stored 
  up 
  in 
  the 
  tubercles 
  themselves 
  is 
  thrown 
  into 
  the 
  

   general 
  circulation 
  and 
  produces 
  fever 
  and 
  characteristic 
  symptoms 
  which 
  go 
  

   to 
  make 
  up 
  what 
  is 
  termed 
  ' 
  a 
  general 
  reaction.' 
  That 
  these 
  poisons 
  stored 
  up 
  

   in 
  the 
  tubercles 
  are 
  in 
  part, 
  at 
  least, 
  derived 
  from 
  the 
  dead 
  or 
  weakened 
  bacilli 
  

   has 
  been 
  shown 
  by 
  the 
  experiments 
  of 
  Babes 
  and 
  Broca. 
  who 
  found 
  that 
  if 
  

   two 
  sets 
  of 
  rabbits 
  be 
  injected 
  with 
  equal 
  quantities 
  of 
  living 
  and 
  dead 
  bacilli, 
  

   the 
  latter 
  react 
  to 
  the 
  tuberculin 
  test 
  at 
  a 
  much 
  earlier 
  period 
  than 
  those 
  

  

  