154 MILK [ix 



in the case of "black" cheese. Again, the bitter 

 flavour which characterises certain cheeses is un- 

 doubtedly due to bacterial life. These faults have 

 been generally attributed in the past to the health 

 and condition of the cow, its food, the condition of 

 the byre, and other causes. These may, no doubt, be the 

 indirect cause, but the direct cause is bacterial life. 



The difficulties with which the cheese -maker 

 has to contend, therefore, are great. He cannot 

 always be sure of a uniform product; for, in spite 

 of all precautions he may adopt, disastrous results 

 may be obtained. To bacterial life also is due the 

 poisonous properties which, unfortunately, cheeses 

 have been found not infrequently to develop. These 

 poisonous properties are due to the production of 

 ptomaines, which are apt to occur in old cheese. 



Imperfect and unsatisfactory as our knowledge at 

 present is of the relation of bacteriology both to 

 butter and cheese making, in this department of 

 research lies the hope of the future of the dairy 

 industry. We have pointed out how very uncertain 

 must necessarily be the results obtained in butter 

 and cheese making under present conditions. This 

 is due to the fact that we have to work so much in 

 the dark in these processes, and thereby incur great 

 risks. While bacteria are the useful servants of the 

 butter and cheese manufacturer, they can also prove 

 his most deadly foes. Unfortunately, it is not always 



