362 THE DAIRYMAN'S MANUAL. 



Caseine contains a large proportion (fifteen and a half 

 per cent) of nitrogen, and during its decomposition in 

 the ripening process some of this nitrogen is converted 

 into ammonia, and it is to this product that the strong 

 and pungent ammoniacal odor of such cheeses as the Lim- 

 burger. Brie, and others that are highly ripened is due. 

 These are all soft unpressed cheese, and are ripened in 

 rooms kept at a temperature of sixty to seventy degrees. 

 These cheeses contain much fat, and as caseine has the 

 ability to produce butyric acid from the oleine of the 

 butter fat, this strongly odorous compound adds to the 

 strength of this class of cheeses. But all highly-cured 

 cheese must contain more or less of these odorous com- 

 pounds as the result of the ripening process. 



The presence of fungi also affects the character of 

 cheese, from their chemical action upon the nitrogenous 

 portions of it. Mold is the principal agent of this char- 

 acter which affects milk and cheese, and the particular 

 variety is known as Penicillium cntstaceum. This plant 

 is very abundantly spread in dairies and wherever cheese 

 is stored. It forms the greenish-blue mold which is 

 seen in old cheese that has been kept in a rather damp 

 place, and it also attacks and feeds upon bread and other 

 moist substances which are rich in albuminous matters, 

 viz., caseine, gluten, albumen, etc. The plant consists 

 of fine, white, silky threads bearing upon their ends a 

 mass of exceedingly small germs or spores which appear 

 as fine dust. These spores are the germs of the plants 

 and when dry are floated off in the air and scattered far 

 and wide. The air contains myriads of these germs too 

 small to be visible, and the dust everywhere contains 

 them in enormous numbers. No place where the air 

 enters is free from them. 



When any albuminous or nitrogenous liquid is exposed 

 to the air, some of these spores fall upon it and immedi- 

 ately begin to grow, in time forming cells which become 



