1 88 PHARMACEUTICAL BACTERIOLOGY 



to be kept, what cattle diseases render the milk unfit for use, how cows and 

 milkers must be prepared for the milking process, etc. The use of pre- 

 servatives is not permitted, because these substances reduce the digesti- 

 bility of the milk and because their use encourages lax and careless methods 

 in the dairying establishments. 



The bovine disease most to be dreaded is tuberculosis. It is very prev- 

 alent among cattle, and the milk from tuberculous cows is a serious menace 

 to the health of those who use it, particularly to susceptible (by inheritance 

 children. The most efficient means of safeguarding the public health 

 against this source of infection consists in removing the infected animals 

 from the herd, with a view to disposing of them by slaughter and burial 

 as soon as circumstances will permit. Where this wasteful method has 

 been employed the results have been discouraging, even when the State 

 recompensed the owner in part for the loss of his stock. The government 

 meat inspection regulations now admit the use of meat of slightly tuber- 

 culous animals, for it is declared that under such circumstances the 

 thorough cooking of meat is an effective safeguard against danger. 



Testing cows for the presence of latent or undeveloped forms of tubercu- 

 losis is simple, safe, and should be rigidly persisted in. Turberculin is in- 

 jected into the neck or shoulder region. If tuberculosis exists there will be 

 a rise in temperature (102 to 104 F.), in the course of from eight to eighteen 

 hours. If the disease is far advanced there may be no reaction, in fact, the 

 reaction is then unnecessary as the indications are already sufficiently 

 positive. 



The tuberculin used is prepared from glycerinated bouillon in which 

 tubercle bacilli have been grown from six to eight weeks. The bouillon 

 culture is first boiled for two hours to kill all the living organisms. It is 

 then filtered under pressure through a germ-proof earthenware filter to re- 

 move the dead bodies of the germs, concentrated by evaporation, a little 

 carbolic acid added, and it is then bottled for distribution. There is no 

 evidence that its use causes an increase in the rapidity of the progress of 

 the disease in animals already affected with tuberculosis, or that it is 

 injurious to them in any other way. It does not even temporarily injure 

 the quality of the milk. 



Preservatives, as boric acid, salicylic acid, benzoic acid, sodium benzo- 

 ate and formalin, are sometimes added to milk to prevent bacterial develop- 

 ment. A very small amount of formalin (1:10,000) is sufficient to check 

 the souring of milk. The others are added in larger amounts (1:1000 or 

 more). These additions are not, as a rule, appreciable through the sense 

 of taste or smell and do not in any way modify the appearance of the milk. 

 In some countries milk preservatives are permissible, in others they are 

 not, and in still others they are permitted provided there is a declaration 



