136 BACTERIA, YEASTS, AND MOLDS 



organic material in a state of partial decay. Any dirt 

 which collects in corners of rooms, in the cracks of floors, 

 or upon shelves in pantries, cellars, etc., is sure to contain 

 bacteria in great quantities. The dirt that clings to the 

 walls and ceilings of rooms is also quite sure to contain 



Fig. S7- A bit of decaying meat highly magnified, show- 

 ing the bacteria feeding upon the material. 



them, and the dirt collected by sweeping the floors is filled 

 with them. 



Bacteria in Food. Bacteria are found in all moist foods, 

 especially in those undergoing the process commonly 

 spoken of as spoiling (Fig. 57). Indeed it is the bac- 

 teria, as we shall presently see, that ordinarily cause 

 this spoiling. Any meat which develops the gamy flavor 



