BACTERIA IN MILK 197 



A tablet containing the lactic acid bacilli, a small 

 quantity of pure culture of the organism, or a "starter" 

 from a previous making is then added to this cooled 

 milk and set aside in a warm room (about 75 F.) over 

 night. The result is a rather agreeable sour milk. 

 Pharmaceutical chemists and laboratories are now 

 supplying tablets and cultures for this purpose. 



Diseases Caused by Polluted Milk. Many diseases are 

 believed to be due to bad or polluted milk. If milk 

 merely carry the germs this is easily understood, but 

 as is the case in the diarrheas of infants, the trouble 

 may lie not with the bacteria introduced with the 

 milk, but with the disturbance of digestion caused 

 by the abnormal chemical conditions brought about 

 by souring. These strange chemical substances 

 so pervert normal digestion that really pathogenic 

 bacteria, the dysentery bacillus group, for example, 

 are able to exert their noxious effects. Streptococci 

 commonly present in the teats, identical with the 

 Streptococcus pyogenes, are said by some to take advan- 

 tage of this disturbed digestion. The examination for 

 streptococci consists in simple staining and finding of 

 them lying in or about pus cells. Health authorities 

 have rules covering this method of examination and 

 the interpretation of results. 



Scarlet fever, although its cause is unknown, is 

 known to spread along milk routes and has at times 

 been traced to a case on a dairy farm. Foot and 

 mouth disease of cattle, another condition of unknown 

 etiology, has been found in children drinking milk 

 from affected cows. The bacillus of diphtheria may 

 live in milk a long time and may be carried along a 



