EXAMINATION OF BACTERIA WITH THE MICROSCOPE. 



19 



etc. In bacteriological work a rather "low-power" | or |-inch 

 objective, and a high-power y^^ inch oil-immersion objective 

 are needed. A ^ or ^ inch dry objective may also occasionally 



Fig. 3. — Microscope. 



be useful. The magnification with the f or |-inch objective is 

 about 75 to 100 diameters; with the J to |-inch 300 to 500 

 diameters; with the yV immersion 750 to 1000 diameters. The 

 magnification varies according to the eye-piece used, as well 



