\m 



STATE BOARD OF AGRICULTURE 



period and retested. In tliree instances the pH score indicates that 

 the milk was in no worse condition after incubation tlian it was before. 

 Tliese were saniiiles of milk which wei'c nnnsnallv good bv this method 

 when tested the first time. 



In certain instances the samples of milk tested with the different 

 kinds of media before and after incubation gave results which indicated 

 that they wei'e as good after the incuibation as 1)ef()re. The samples 

 mav be classitied as shown in Table No. 1. 



TABLE I. 

 Condition of milk samples upon retest a'ter short incubation period. 



How Tested 



Meat extract agar. . 

 Milk powder agar A 



Bacto agar 



Meat infusion agar. 

 pH score 



Poorer 



20 

 20 

 21 

 22 

 29 



No Change 



Better 



12 

 11 

 11 



y 







It seems that after tlie tr-eatment which the above samples received, 

 eflicient methods should show the samples iu worse condition uj)on re- 

 test. A few of the samples which were in very good condition at the 

 start might show no change upon retest, but certainly a reliable method 

 should not indicate that a third of the samples were in improved con- 

 dition. 



Many investigations have been made to determine the most suitaible 

 media for milk work. It has usually been concluded in these studies 

 that the method giving tlie highest counts is most efficient. It is argued 

 that the medium giving the highest counts comes closest to giving 

 counts which represent all of the bacteria present in the milk. There is 

 a failure to agree upon the medium giving the highest counts. The 

 reasons for this failure are considered below. 



