46 The Story of the Bacteria 



very undesirable compounds in the fluids. 

 So the manufacturer has to be on the alert, 

 and at the right moment come to the rescue 

 of his army of servitors, the yeast plants, 

 and introduce into his beer some chemical 

 substance which is innocuous to them but 

 deadly to the intruding bacteria. Or he may 

 raise his wine at a certain period to such a 

 temperature as will suffice to kill the bacteria 

 but not injure the flavor of the already fer- 

 mented juice. Here again as in the case of 

 the farmer we see the bacteria coming into 

 conflict with the purposes of their earth- 

 neighbor man . 



Some of the bacteria are great lovers of 

 oxygen, and if they are shut up in a little cell 

 containing a few drops of water in which a 

 bubble of air has been enclosed, after a while 

 it will be found that those forms which are 

 capable of locomotion have made their way 

 from all parts of the fluid, which is a veritable 

 ocean to them, and are closely clustered 

 around the air bubble, jostling and bumping 

 against one another in the most reckless way. 

 It seems almost as if this rush towards the 



