2O8 BACTERIA AND OTHER MICROORGANISMS IN CHEESE. 
water being commonly used, although vinegar is sometimes put into 
the water. The surface is thus kept constantly moist. Because 
of this constant moisture on the surface of the cheese, molds cannot 
grow upon it, for they need a damp, not a wet surface; but a quantity 
of bacteria grow instead. These ripen the cheese, doubtless by 
the secretion of chemical ferments, although the process has not 
as yet been fully studied. The resulting cheese develops very 
high flavors, closely resembling those of decay, and the cheeses 
rapidly putrefy when they become old. If they are marketed 
at the right stage the flavors are not strong enough to be disagreeable, 
and many persons are very fond of them. The Limburger type 
of cheese includes Backstein and some others. 
PRACTICAL RESULTS. 
The practical application of bacteriology to cheese-making is 
just in its infancy, and it is quite impossible to determine the extent 
of its development in the future. As already pointed out, cheese- 
makers, in the last few years, have been using pure cultures of lactic 
acid bacteria as starters to insure a more complete and more uniform 
souring of the curd. This practice is rapidly growing. The lactic 
starters have two purposes. First, the growth of the acid organisms 
checks the growth of other bacteria that would be likely to spoil 
the cheese, and this check seems to be quite necessary for the proper 
ripening and for the preventing of faults. Second, the formation 
of lactic acid appears to be a needed step in the chemical changes 
that constitute the ripening. Hence, the use of a good starter of 
acid organisms has a reasonable foundation, and we may confidently 
assume that the practice of using starters will increase. In the 
making of the Edam cheese of Holland, the practice of using slimy 
whey to aid the ripening of the cheese has become very extended. 
The slimy whey is a culture of bacteria in whey, and is, therefore, 
simply another method of using a bacterial starter to control the 
cheese-ripening. It hastens the ripening and makes it more uniform, 
but it does not improve the cheese. In the manufacture of Roque- 
fort cheese, mold cultures are- intentionally added to bring about 
