50 BOARD OF AGRICULTURE. [Pub. Doc. 



Bacteria, however, resist destruction by heat for a long time. 

 Two and even more hours at boiling point (212° F.) is required 

 to render all vegetables and meats proof against spoiling. 

 Molds are generally killed at the temperature of boiling water. 



Bacteria are so small that they can only be seen with a 

 microscope, and they reproduce themselves with amazing 

 rapidity. 



One bacterium under favorable conditions will reproduce itself 

 about 20,000,000 times in the course of twenty-four hours. Ac- 

 cordingly, certain vegetables spoil more rapidly because they 

 furnish a better medium for bacterial growth. 



The reproduction of bacteria is brought about by one of two 

 processes, — the germ either divides itself into two parts, 

 making two bacteria where one existed before, or else re- 

 produces itself by means of spores. These spores are compared 

 to the seeds of an ordinary plant, and they present the chief 

 diflSculty in canning vegetables, meats and fish. While the 

 parent bacteria are readily killed at the temperature of boiling 

 water these spores retain their vitality for a long time even at 

 that temperature, and in cooling will germinate, and the newly 

 formed bacteria will begin their destructive work. Therefore 

 it is necessary, in order to completely sterilize a vegetable, meat 

 or fish, to heat it to the boiling point of water and keep it at 

 that temperature for two or more hours. 



This boiling of foods and dishes to free them from all germ 

 life is called sterilization. Unless fruits, meats and vegetables 

 are boiled long enough to destroy this germ life they are not 

 sterile and will surely spoil. Once sterilized the food and the 

 inside of the jar must be protected from the air, which as I 

 said before is filled with these tiny microbes. Unless it is 

 absolutely and permanently protected it will surely be attacked 

 by these germs and it will spoil. 



Jars. 



It is not necessary to protect all sterilized foods from the 

 light, but in order to keep them sterile they must be encased 

 in an air-tight jar. This jar must not only be air-tight at the 

 time of canning, but must remain so until opened. The first 

 requisite for successful canning is a good jar. There are many 



