164 PROFITABLE DAIRYING 



How the germs are destroyed. Tubercle bacilli 

 cannot live at a temperature of 160 degrees F., 

 and in direct sunlight they die in less than two 

 hours. Pasteurizing whey and skim-milk, that 

 is, heating it to 160 degrees F., will kill these 

 germs and prevent the spread of disease from 

 factory centers. Plenty of sunlight, fresh air, 

 and the use of whitewash in stables are effective 

 means of preventing the rapid spreading of the 

 disease in herds. 



However, the disease cannot be communicated 

 from one vicinity to another except through the 

 introduction of diseased animals into the neigh- 

 borhood, and some states have required that all 

 animals imported within their borders should 

 pass the tuberculin test. Now what is this test? 



The tuberculin test. The United States De- 

 partment of Agriculture and some of the state 

 experiment stations are engaged in preparing 

 and distributing tuberculin, a coffee-colored 

 liquid, which if injected under the skin of 

 infected animals will cause a rise in the ani- 

 mal's temperature. No change is produced, how- 

 ever, by injecting this substance under the skin 

 of a healthy animal. During the test the animals 

 must be kept in as nearly a normal condition 

 as possible. Before injection four temperatures 

 are taken with a clinical thermometer, two hours 

 apart. These temperatures are taken by insert- 



