398 



BACTERIA 



Practically all bodies of water on the surface of the earth contain 

 great numbers of bacteria. The numbers in different kinds of water 



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•slant Smza^rs 



•Stab Cvi"\"turcs 



Two types of inoculations, smears and stabs, are made on slant cultures. After the media are 

 incubated, the germs grow into colonies, each having a characteristic form and shape. 



vary according to the location of the water. In spring water, the 

 number of bacteria is relatively small, but in water into which sew- 

 age from cities drain, the number is extremely large. Sometimes 

 bacteria in water contaminated with sewage are disease producing. 

 The soil that has been well cultivated is usually rich in bac- 

 teria. The deeper layers of soil contain few or no bacteria. 

 Where the soil is drv and sandv, there are relativelv few bac- 

 teria ; where it is moist and loamy, they are abundant. They 

 are found in great numbers around the bodies of dead animals or 

 in soil that contains decaying roots of plants. 



