EXAMINATION OF BACTERIA WITH THE MICROSCOPE. 19 



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

 objective, and a high-power T V inch oil-immersion objective 

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



FIG. 3. Microscope. 



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

 about 75 to 100 diameters; with the J to J-inch 300 to 5oc 

 diameters; with the y 1 -^ immersion 750 to 1000 diameters. The 

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



