226 BACTERIA 



the extensive list of bacteria found in cheese are of course 

 varied, more varied indeed than is the case with milk. For 

 there are, in addition to the organisms contained in the milk 

 brought to the cheese factory, the following prolific sources, 

 viz., the vats and additional apparatus; the rennet (which 

 itself contains a great number); the water that is used in 

 the manufacture. 



In addition to the abnormalities due to gas, there are also 

 other faulty types. The following chromogenic conditions 

 occur : red cheese, due to a micrococcus ; blue cheese, pro- 

 duced, according to Vries, by a bacillus ; and black cheese, 

 caused by a copious growth of low fungi. Bitter cheese is 

 the result of the Micrococcus casei amari of Freudenreich, a 

 closely allied form of Conn's micrococcus of bitter milk. 

 Sometimes cheese undergoes a putrefactive decomposition, 

 and becomes more or less putrid. These latter conditions, 

 like the gassy cheeses, are due to the intrusion of bacteria 

 from without, or from udder disease of the cow. Healthy 

 cows, clean milking, and the introduction of pure cultures 

 are the methods to be adopted for avoiding ** diseases '* of 

 cheese and obtaining a well-flavoured article which will 

 keep. 



Finally, we may quote five conclusions from the prolonged 

 researches of Mr. Lloyd ^ which cannot but prove helpful to 

 the Cheddar cheese industry in England : 



1. To make Cheddar cheese of excellent quality, the 

 Bacillus acidi lactici alone is necessary ; other germs will 

 tend to make the work more rather than less difficult. 

 Hence scrupulous cleanliness should be a primary consider- 

 ation of the cheese-maker. 



2. No matter what system of manufacture be adopted, two 

 things are necessary. One is that the whey be separated 

 from the curd, so that when the curd is ground it shall con- 

 tain not less than 40 per cent, of water, and not more than 



^Journal of Bath and West of England Society , 1893, 1895, and 1897. 



