﻿CoMinssiONER 
  OF 
  Agkicultuke. 
  541 
  

  

  As 
  tuberculin 
  is 
  a 
  commercial 
  product, 
  it 
  can 
  be 
  procured 
  and 
  

   used 
  in 
  private 
  practice 
  by 
  those 
  who 
  are 
  not 
  competent, 
  profes- 
  

   sionally, 
  to 
  do 
  so. 
  It 
  is 
  the 
  errors 
  incident 
  to 
  ignorance, 
  or, 
  worse, 
  

   deliberate 
  deviations 
  from 
  truth, 
  that 
  have 
  led 
  to 
  most 
  of 
  the 
  

   charges 
  against 
  its 
  use. 
  Tuberculin 
  cannot 
  give 
  knowledge 
  to 
  the 
  

   ignorant 
  or 
  ^^rtue 
  to 
  the 
  corrupt, 
  but, 
  like 
  other 
  chemical 
  rea- 
  

   gents, 
  when 
  the 
  conditions 
  are 
  right 
  it 
  produces 
  its 
  specific 
  effect. 
  

   It 
  is 
  the 
  task 
  of 
  the 
  tester 
  to 
  see 
  that 
  this 
  effect 
  is 
  differentiated 
  

   from 
  somewhat 
  similar 
  manifestations 
  which 
  may 
  arise 
  from 
  

   other 
  causes, 
  and 
  that 
  its 
  reaction 
  is 
  accurately 
  recorded. 
  Tuber- 
  

   culin 
  cannot 
  disclose 
  irregularities, 
  but 
  if 
  it 
  is 
  put 
  in 
  the 
  hands 
  of 
  

   those 
  who 
  know 
  its 
  powers 
  and 
  how 
  to 
  use 
  it, 
  it 
  will 
  take 
  a 
  knave 
  

   indeed 
  to 
  prevent 
  its 
  reaction 
  or 
  to 
  disguise 
  the 
  same 
  from 
  him 
  

   who 
  applies 
  it. 
  

  

  If 
  we 
  exclude, 
  as 
  we 
  should, 
  the 
  objections 
  to 
  tuberculin 
  due 
  to 
  

   the 
  deliberate 
  intention 
  to 
  deceive, 
  and 
  again 
  search 
  the 
  records, 
  

   we 
  find 
  that 
  even 
  the 
  unskilled 
  and 
  often 
  careless 
  user 
  obtains 
  

   most 
  remarkably 
  accurate 
  results. 
  Omitting 
  practically 
  all 
  of 
  the 
  

   precautions 
  enjoined, 
  and 
  following 
  the 
  shorter 
  procedure 
  of 
  most 
  

   practitioners, 
  we 
  cannot 
  find 
  positive 
  evidence 
  of 
  5 
  per 
  cent, 
  of 
  

   error. 
  AVhen 
  but 
  one 
  initial 
  and 
  but 
  three 
  or 
  four 
  subsequent 
  tem- 
  

   peratures 
  are 
  taken 
  and 
  little 
  or 
  no 
  attention 
  is 
  paid 
  to 
  the 
  other 
  

   influencing 
  conditions, 
  an 
  error 
  of 
  not 
  more 
  than 
  5 
  or 
  even 
  of 
  10 
  

   per 
  cent, 
  speaks 
  in 
  unmistakable 
  terms 
  for 
  the 
  efficiency 
  of 
  this 
  

   agent. 
  

  

  Tuberculin 
  has 
  been 
  thought 
  to 
  be 
  inefficient 
  because 
  in 
  certain 
  

   dairies 
  where 
  it 
  has 
  been 
  used 
  and 
  the 
  reacting 
  animals 
  removed 
  

   the 
  disease 
  h-as 
  subsequently 
  appeared. 
  In 
  all 
  such 
  herds 
  of 
  which 
  

   I 
  have 
  knowledge 
  there 
  is 
  a 
  reasonable 
  explanation 
  for 
  such 
  a 
  

   recurrence 
  in 
  one 
  or 
  more 
  of 
  the 
  three 
  following 
  conditions, 
  viz.: 
  

   (1) 
  The 
  advanced 
  cases 
  which 
  did 
  not 
  react 
  were 
  not 
  detected 
  on 
  

   physical 
  examination 
  and 
  removed, 
  or 
  (2) 
  tie 
  disinfection 
  of 
  th« 
  

   premises 
  was 
  imperfectly 
  done, 
  or 
  (3) 
  certain 
  animals 
  may 
  at 
  the 
  

   time 
  of 
  the 
  test 
  have 
  been 
  infected, 
  but 
  the 
  lesion 
  or 
  tubercle 
  not 
  

  

  