308 A YEAR IN SCIENCE 



Sometimes in foods, bacteria and other parasites are 

 living. Most of these are fortunately destroyed at the 

 temperature of boiling water. Trichina and tapeworm 

 are two parasitic worms sometimes present in meats 

 in a so-called resting stage. Trichina is found in pork. 

 When diseased pork, poorly cooked, is eaten, these 

 small worms again become active. They bore their way 

 through the walls of the alimentary canal and finally 

 settle in the muscles. This produces a painful and 

 sometimes fatal disease. The tapeworm is found in 

 pork and beef. It attaches itself by means of hooks 

 to the walls of the alimentary canal, remains there 

 and grows. It can readily be removed and no serious 

 results follow. 



Decay in meat is brought about by bacteria. If the 

 process has continued far enough poisons, called 

 ptomaines, are produced. The bacteria, but not the 

 poisons, can be rendered harmless by heat. As a result 

 ptomaine poisoning frequently follows the eating of 

 tainted meats, especially fish, and spoiled ice cream. 



Milk can be rendered harmless by heating it for half 

 an hour in water at a temperature of 140F. to 160 F. 

 It should then be cooled and kept cool. .This process, 

 known as pasteurization, kills the bacteria and at the 

 same time obviates some of the disadvantages of boiling 

 milk. 



