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IV. 

 THE MICROSCOPE AND ITS COMPONENT PARTS. 



The stand Coarse adjustment by rack and pinion. 



Fine adjustment by micrometer screw. 

 The optical part mirror, Abbe condenser with iris 

 diaphragm, objectives, eye-pieces. 



(Structure of the Abbe condenser its object. 



In examining unstained specimens contract 



the diaphragm. 

 In examining stained specimens open the 



diaphragm. 

 Requirements of good objectives : 



Magnification, defining power, resolving power. 

 Achromatic and apochromatic objectives. 

 Homogeneous oil-immersion objectives advant- 

 ages. 



The cedar oil must be removed at the close of the 

 day's work by touching the lens carefully with soft filter 

 paper. 



Slides and cover-glasses for microscopic work must be 

 rigidly clean. The cover-glasses should be kept in alco- 

 hol and wiped dry when needed. If surface is at all 

 greasy, heat the cover-glasses with sulphuric acid and 

 potassium bichromate, wash well with water and transfer 

 to alcohol. 



EXAMINATION OF BACTERIA IN HANGING 



DROPS. 



This is intended to show the bacteria in the living 

 condition their form and arrangement, presence or 

 absence of motion, the appearance of the protoplasm, 

 division of the cells, sporogenic granules, spores, etc. 



