Bacteria and Cheese Making. 183 



lactic bacteria, farming from it propionic acid and car- 

 bon dioxide, the latter gas being the cause of the hole or 



"eye." 



The " eye "-forming organisms cannot grow in the 

 presence of any amount of salt, hence, if salt is added 

 directly to the curd, the cheese is likely to be ''blind" 



FIG 38. Swiss CHEESE. 



Normal development of "eyes" in a Swiss cheese. The eyes 

 are generally as large as a cherry. 



or free from holes. The eyes are formed not at the time 

 gas holes are produced in a cheddar cheese, i. e. } early in 

 the ripening process, but after a lapse of three or four 

 weeks. They are most abundant in the middle of the 

 cheese since the manner of salting is such as to inhibit 

 their formation near the surface. The eye-forming bac- 

 teria may have some effect on the flavor of the cheese. 



The Swiss maker encounters the same troubles as does 

 the cheddar maker. Gassy cheese is more prevalent in 

 the Swiss than in the cheddar industry, since the maker 

 cannot call to his aid the methods used by the cheddar 

 maker, viz., the addition of a heavy starter, the washing 

 of the curd, etc. It is 'especially important that the 

 quality of the milk be first class in every respect, and 



