24 CLEAN MILK 



The liquefiers also liquefy the substance on which germs are 

 commonly grown in the laboratory, i. c, gelatine; hence their name. 



The putrefactive germs or liquefiers may amount to 20 or 50%. 

 of the germs present in milk at the end of 24 hours (Conn), 

 but from this time on they are commonly crowded out by growth 

 of the lactic acid bacteria and gradually disappear. 



There are a great number of germs in milk which apparently 

 have no effect upon its character and also are not harmful to the 

 consumer. It is practically impossible to discover the germs of 

 special diseases in milk with any certainty, so that besides recogniz- 

 ing the chief types of germs — the lactic acid germs, the putrefactive 

 germs, and miscellaneous germs whose action is unknown to us — 

 the best that can be done at present is to estimate the number of 

 germs in milk per cubic centimeter. Large numbers of miscellan- 

 eous and putrefactive germs signify that the milk is contaminated 

 with filth and is most dangerous. Large numbers of lactic acid 

 germs indicate that the milk has not been kept cool enough or is 

 old. Freedom from any considerable number of germs is a pretty 

 certain sign that the milk has been drawn from the cow and handled 

 in a cleanly manner; has been properly cooled and is likely to be 

 uncontaminated with disease-germs. This is the justification of 

 cities which require that milk shall not contain more than a specified 

 number of germs (bacteria) to the cubic centimeter. 



Thus the law in force in Boston requires that milk sold in that 

 city shall not contain more than 500,000 germs to the cubic 

 centimeter. 



It has generally been admitted that it is difficult to obtain any 

 large supply of milk which shall certainly contain less than 10,000 

 germs to the cubic centimeter. In various parts of the United States 

 milk of such purity is now sold and is often called " Certified Milk." 

 The name " Certified Milk " originated with Henry L. Coit, M.D. 

 He established a commission of medical men in Newark, N. J., in 

 1893, who made an agreement with a dairyman of Caldwell, N. J., 



