EXPERIMENTAL 

 DAIRY BACTERIOLOGY 



CHAPTER I 



CULTURAL TECHNIQUE 



Glassware. In bacteriological work a large amount of 

 glassware must be used. It is desirable to employ the most 

 convenient and economical types of tubes, dishes, etc. The 

 test tubes used for the storage of media for culture work are 

 not the ordinary thin-walled test tubes of the chemical labo- 

 ratory, but are made of much heavier glass and without the 

 lip. Such tubes of thick glass are not so easily broken in 

 handling and yet will withstand the action of heat. A tube 

 120 mm. long and 15 mm. internal diameter is a convenient 

 size, and of sufficient capacity for nearly all purposes. If it 

 is desirable to have a tube holding 10 cc., tubes of 18 mm. 

 diameter will be required. The tubes in use in the laboratory 

 should always be of the same length, 120 mm. or 150 mm. 

 The tube described is usually known as the " board of health 1 ' 

 pattern. 



Petri dishes should have an internal diameter of 90 mm., 

 and should be 15 mm. high ; the covers should be 10-12 mm. 

 deep, and should be 2-3 mm. greater in diameter than the 

 bottoms. The bottoms of the Petri dishes should be perfectly 

 flat. The glass from which tubes and dishes are made should 



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