92 THE STORY OF GERM LIFE. 



demonstrate beyond peradventure that the ab- 

 normal ripening of cheese is due primarily to the 

 growth of improper species therein. Quite a long 

 list of species of bacteria which produce abnormal 

 ripening have been isolated 

 from cheeses, and have 

 been studied and experi- 

 mented 'with by bacteriolo- 

 gists. As a result of this 

 study of abnormal ripening, 

 there has been suggested a 

 method of partially con- 

 FIG. 24. Dairy bacterium trolling these remedying 



producing: -swelled" them> The met hod COn- 

 cheese. . ^ . . . . 



sists simply in testing the 



fermenting qualities of the milk used. A small 

 sample of milk from different dairies is allowed to 

 stand in the cheese factory by itself until it un- 

 dergoes its normal souring. If the fermentation 

 or souring that thus occurs is of a normal charac- 

 ter, the milk is regarded as proper for cheese 

 making. But if the fermentation that occurs in 

 any particular sample of milk is unusual; if an 

 extraordinary amount of gas bubbles are pro- 

 duced, or if unpleasant smells and tastes arise, , 

 the sample is regarded as unfavourable for cheese 

 making, and as likely to produce abnormal ripen- 

 ing in the cheeses. Milk from this source would 

 therefore be excluded from the milk that is to be 

 used in cheese making. This, of course, is a ten- 

 tative and an unsatisfactory method of control- 

 ling the ripening, and yet it is one of some prac- 

 tical value to cheese makers. It is the only 

 method that has yet been suggested of control- 

 ling the ripening. 



Our bacteriologists, of course, are quite con- 



