Exercise I 



LIVING CELLS (1) 5 



THE COMPOUND MICROSCOPE 



Ocular: 



{5X or 10X) 



Coarse adjustment knob 



Fine adjustment 

 knob 



Objectives: high 

 power (4 mm 

 40 X, and low 

 power (16 mm), 10 X 



Condenser with 

 iris diaphragm 



Mirror: one 

 side concave,— 

 the other flat 



Base 



(7) When examining permanent slides, you 

 may find it more comfortable to tilt the micro- 

 scope toward you, at an angle with its base. 

 For work with fresh preparations, always keep 

 the stage of the microscope horizontal. 



(8) It is good practice to keep both eyes open 

 when looking through the microscope. You 

 will soon learn to disregard the image from the 

 "off" eye, and so will avoid the strain of holding 

 that eye closed. 



(9) Dirty lenses give poor results. Clean them 

 only with the special lens paper which is pro- 

 vided, not with your handkerchief, Kleenex, or 

 anything else. If after it is gently wiped with 



lens paper your microscope still does not yield 

 a clear image, ask your instructor to help. 



(10) The magnification of any combination of 

 objectives and oculars is the product of the 

 magnifications of the separate components. 

 Thus a lOX ocular combined with the low- 

 power, lOX objective yields a total magnifica- 

 tion of 100 diameters. Each of the objectives 

 is marked with its magnification and the dis- 

 tance from the object at which it yields an 

 approximate focus. The low-power objective is 

 in focus at about 16 millimeters above the object, 

 the high-power (44 X) objective at about 4 milli- 

 meters above the object. 



