A LABORATORY GUIDE FOR GENERAL BOTANY 



(m) Don't shut one eye when looking through 

 the instrument. Ability to work with both 

 eyes open is easily acquired, is much less 

 tiring, and is an advantage in many ways. 



(n) Never use high powers when low powers will serve. 



(o) Examine all objects with the low power first, 

 then with the high power, if necessary. 



(p) Never set the instrument away with a micro- 

 scopic slide under the objective, nor with the 

 high-power objective over the aperture. 



(q) When the laboratory period is over, remove 

 the preparation you have been studying, and 

 leave the microscope either with the low- power 

 objective over the aperture, or, if a dust-proof 

 nose-piece is used, then with the objectives 

 sidewise. 



