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ESSENTIALS OF BACTERIOLOGY 



Microscopic. Use a low-power lens, with the Abbe 

 nearly shut out that is the narrowest blender. The stage of 

 the microscope should be of such size as to carry a Petri 

 saucer easily upon it. 



The second dilution or third plate is usually made use of 

 that one containing the colonies sufficiently isolated. 



These isolated ones should be sought for, and their appear- 

 ance well noticed. 



There may be two or three forms from the same germ, the 

 difference due to the greater or less amount of oxygen that 



Fig- 33- Microscopic appear- 

 ances of colonies. 



Fig. 34. Klatsch preparations. 



they have received, or the greater or less amount of space 

 that they have had to develop in. 



The microscopic picture varies greatly; now it is like the 

 gnarled roots of a tree, and now like bits of frosted glass; 

 some bacteria have quite characteristic colonies (Fig. 32). 



Impression or "Klatsch" Preparations. In order 

 more thoroughly to study a certain colony and to make a 

 permanent specimen of the same, we press a clean cover-glass 

 upon the particular colony, and it adheres to the glass. It 

 can then be stained or examined. The Germans give the 

 name of " Klatsch" to such preparations. 



Fishing. To obtain and examine the individual members 



