DAIRY MEETIXG. II9 



milk is secured and handled. Clean milk can only be secured 

 by clean milkers who use clean utensils and who do their work 

 under clean cows and in a clean atmosphere. There are various 

 ways by which cleanliness may be secured. The expense of 

 cleanliness need not be great, but the absence of it may be and 

 sometimes is most damaging to a dairyman and to a community. 



Basing my opinion upon the work of many clean and success- 

 ful dairymen I believe a perfect certified milk should not con- 

 tain over one thousand bacteria per cubic centimeter. I also 

 believe a perfect market milk should not contain over ten thou- 

 sand bacteria per cubic centimeter. Milks and creams contain- 

 ing bacteria in excess of the above mentioned standards are 

 scored according to the conditions found (see score card for 

 milk) but no certified milk containing over forty thousand 

 bacteria per cubic centimeter should be entitled to a single point 

 on the score card. 



The number of bacteria in milk or cream may be determined 

 in the following manner: 



The bottle of milk is vigorously shaken so a fair sample can 

 be secured, i c. c. pipette (sterilized) is filled and the sample 

 is transferred to a flash containing 99 c. c. of sterilized water. 

 (The milk is then diluted 100 times). A definite amount of 

 milk thus diluted (.1 c. c. or i c. c.) is then transferred to a 

 sterilized petri dish. To the diluted milk is added a culture 

 media (2% lactose agar) melted or in a liquid condition. The 

 diluted milk and culture media are well mixed. The culture 

 media solidifies as its temperature lowers and each individual 

 germ is made stationary in the solidified jelly. The dishes and 

 contents (milk and culture media) are then placed in an incu- 

 bating oven at about 98°- 100° F. where for two days the 

 germs are allowed to grow. At the end of that time each 

 original germ will have multiplied a sufficient number of times 

 to form a colony large enough to be seen with the naked eye. 

 By the aid of specially devised apparatus the colonies are 

 counted. The necessary calculations are made (according to 

 the dilution of the milk sample) and the total number of germs 

 originally in the milk is known. 



