60 HOUSEHOLD BACTERIOLOGY 



in ptomaine poisoning. This would be putrid cheese. 



As with cream, so the cheese curd may be inoculated 

 with the particular germ which, by its growth and life 

 processes, is known to give the desired flavor, just as 

 a person may be inoculated with a certain disease germ. 

 In both the processes are similar, although the results 

 are different. 



If cheese be made from boiled or Pasteurized milk 

 or from that to which a germicide has been added, the 

 ripening process does not go on, showing that the 

 living micro-organism is necessary to the production 

 of the desired flavors. 



Pure cultures are now used for cheese ripening and 

 therefore cheeses that have heretofore been imported, 

 because the species of bacterium necessary was not 

 native to this country, may now be made here when the 

 conditions of growth are understood. 



Butter and cheese are possibly the most common 

 foods whose desirable and varied flavors are due to 

 bacteria and molds, but there are others where their 

 work is often productive of a pleasant taste. 



Anyone who has seen a cider mill in operation in 

 the country or has seen the cider made "while you 

 wait" at a city fair knows the process by which the 

 whole apple is crushed and the juice extracted. Such 

 juice must, of course, be seeded with wild yeasts and 

 with bacteria which were on the skin of the fruit or 

 in the air. When it runs directly from the press, it 



