so 



BACTERIA, YEASTS, AND MOLDS 



of the peculiarly flavored products characteristic of certain 

 forms of decay, rot, or putrefaction. 



It must not be understood, however, that putrefaction 

 is produced wholly by the action of molds, even in the 

 materials on which molds are visibly growing ; for another 

 class of organisms to be considered later, the bacteria, is 

 more commonly concerned in putrefaction. But molds 

 contribute largely to the development of putrefaction, and 

 in the case of some materials, as fruits, molds are prac- 

 tically the sole cause of this phenomenon. 



Molds upon Food not necessarily Unwholesome 



The result of these various changes is that almost all 

 foods are soon spoiled if molds are allowed to grow upon 



them for any considerable 

 time. They rapidly change 

 in flavor, odor, and in ap- 

 pearance, and eventually 

 the putrefaction or decay 

 makes them utterly value- 

 less. If, however, the 

 molding is checked quickly 

 and the food preserved from 

 further molding, or if it is 

 consumed at once, there 

 is no reason why the food should not be utilized, for the 

 mold itself is not particularly unwholesome. We may 

 consume food that has begun to mold without its produ- 

 cing any ill effects upon us, provided that the molding has 

 not extended too far and that we do not eat a great quantity 



Fig. 20. A bit of American cheese. 

 No molds are present. 



