170 ADMINISTRATIVE SECTION 



and kept under observation. If they are proved to 

 be tuberculous then they are slaughtered. If this 

 strict inspection is carried out universally and syste- 

 matically, we will soon have got rid of our tuberculous 

 cattle. As to whether trained veterinary surgeons 

 or skilled inspectors should be employed in this work, 

 it is not my province to advise, but for the examina- 

 tion of the milk there can be no question that it 

 should be wholly in the hands of expert bacteriologists, 

 for this examination needs skill, training, and con- 

 siderable experience. 



The three main difficulties to be met with are : 



(1) The presence of extremely few bacilli. 



(2) The presence of acid-fast bacilli which morpho- 

 logically resemble B. tuberculosis. 



(3) The presence of " non-acid-fast" B. tuberculosis. 



(1) When the bacilli are very scanty, and this is 

 the common condition, it is necessary to centrifugalize 

 considerable quantities of the milk (as a routine 

 practice, I centrifugalize 1,000 c.c.), and this centri- 

 fugalization should be carried out from thirty to sixty 

 minutes at a speed of from 2,000 to 3,000 revolutions 

 per minute. The examination of the deposit must be 

 done carefully and often for prolonged periods before 

 any bacilli are found, and in many cases failure 

 to find the organism after a prolonged search does 

 not mean that they are absent. A negative result of 

 a microscopical examination is of very doubtful value ; 

 though if the special cow from which the milk has 

 been taken shows no signs of tuberculosis, the 

 negative result may be interpreted favourably. But 

 if inoculation into animals is discouraged, many cows 

 infected with tuberculosis will escape detection. 



(2) The presence of acid-fast bacilli which do 

 not produce tuberculosis is common in many mixed 

 samples. These are probably derived from extraneous 

 sources and, where strict cleanliness is observed, they 



