CHAPTER II. 



BACTERIA IN MILK. 



The term bacteria is applied to. the smallest of living 

 plants, which can be seen only under the highest powers 

 of the miscroscope. Each bacterium is made up of a 

 single cell. These plants are so small that it would 

 require 30,000 of them laid side by side to measure an 

 inch. Their presence is almost universal, being found 

 in the air, water, and soil; in cold, hot, and temperate 

 climates; and in living and dead as well as inorganic 

 matter. 



Bacteria grow with marvelous rapidity. A single bac- 

 terium is capable of reproducing itself a million times 

 in twenty-four hours. They reproduce either by a simple 

 division of the mother cell, thus producing two new cdls, 

 or by spore formation in which case the contents of the 

 mother cell are formed into a round mass called a spore. 

 These spores have the power of withstanding unfavorable 

 conditions to a remarkable extent, some being able to 

 endure a temperature of 212° F. for several hours. 



Most bacteria require for best growth a moist, warm, 

 and nutritious medium such as is furnished by milk, in 

 which an exceedingly varied and active life is possible. 



In nature and in many of the arts and industries, 

 bacteria are of the greatest utility, if not indispensable. 

 They play a most important part in the disintegration of 

 vegetable and animal matter, resolving compounds into 

 their elemental constituents in which form they can again 



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