50 BUTTER-MAKING. 



For this purpose, it is sufficient to classify the bacteria into 

 three groups; viz., (1) those which are harmful to the butter- 

 making industry, (2) those which are beneficial, and (3) those 

 which are indifferent, or produce neither good nor bad results. 



From the farmer's or milk-producer's standpoint, none 

 of these bacteria are desirable. Each milk-producer should 



FIG. 9. Shows a plate exposed one-half minute under a cow's udder treated 

 with a 5% solution of carbolic acid. (Bui. 87, Nebraska.) 



make it a point to prevent their entrance and suppress their 

 development in milk and cream to as great an extent as pos- 

 sible. The creamery operator should endeavor to suppress 

 all of the harmful germs, and foster the development of the 

 desirable ones. 



The germs which are desirable belong chiefly to the acid- 

 producing types. They are often called lactic ferments. 



The harmful bacteria include those which produce bitter 

 milk, red milk, blue milk, yellow milk, slimy milk, etc. There 



