148 BACTERIA, YEASTS, AND MOLDS 



liquids that soak down into the soil or evaporate, leaving 

 only a small residue. This is the general phenomenon of 

 putrefaction, ending in complete decay. 



Advantages from Incipient Decay. Although this pro- 

 cess of decay may be a somewhat rapid one, it actually 

 takes place by steps, one after another. The breaking 

 down of the food under the action of bacteria is not a 

 sudden falling of the molecules into fragments but a pro- 

 cess that takes considerable time and presents a number 

 of intermediate steps between the original food and the 

 final condition of decay. As the bacteria begin to act 

 upon the food it is not at first necessarily ruined or even 

 injured. At the beginning of the process the new prod- 

 ucts are quite different from those that appear later, and 

 it may happen that those first produced give to the food 

 a slight flavor which, instead of injuring its character, 

 actually improves it. 



The presence of a certain amount of flavor in our foods 

 is very desirable, and even necessary. Pure foods with- 

 out flavors cannot be properly digested and absorbed, a 

 certain amount of flavor being needed to stimulate the 

 digestive organs. Some of the flavors arising in the early 

 stage of decomposition are of a character that is enjoyed 

 by the human palate. For example, the so-called gamy 

 taste of meat is a flavor which some people enjoy very 

 much, while others dislike it. This gamy taste is simply 

 the beginning of decomposition, and is due to the fact 

 that the meats have been kept until the bacteria have 

 begun to act upon them and to produce the incipient 

 stages of putrefaction. In this early period the flavors 

 are not very strong and not particularly unpleasant ; but 



