104 PHARMACEUTICAL BACTERIOLOGY. 



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 of disposing of them by slaughter and burial as soon as cir- 

 cumstances 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 admit the use of meat of slightly tuberculous animals for food, 

 for it is declared that under such circumstances the 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. Tuberculin 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 remove 

 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 benzoate 

 and formalin, are sometimes added to milk to prevent bacterial development. 

 A very small amount of formalin (i: 10,000) is sufficient to check the souring 

 of milk. The others are added in larger amounts (i : 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 to that effect and the 

 amount does not exceed a definite percentage, as provided by law. 



In England, a limited amount of certain preservatives added to milk is 

 permissible, the argument being that it is better to supply preserved milk than 

 milk loaded with germs. This argument has its commendable features. In 

 very large, congested cities like London, New York and Chicago, it is im- 

 possible to supply the poor with certified milk or milk which can be kept free 

 from excessive germ development until it is wanted for consumption. 



Boiling the milk for twenty minutes kills the germs, but unfortunately the 

 boiling temperature produces certain changes which greatly reduce the food 

 value of the milk, besides the germicidal properties of the milk are destroyed, 



