i4 
PHARMACEUTICAL BOTANY 
immersion oil (slightly evaporated cedar oil) should be placed on the 
cover glass directly above the object and the body tube should be 
run down with the coarse adjustment until the front lens of the 
immersion objective enters the drop and comes almost into contact 
with the cover glass. This should be done while watching the objec¬ 
tive. Then look through the ocular and draw the objective up with 
the fine adjustment until the object comes into focus. 
RULES FOR THE CARE OF THE MICROSCOPE 
1. In carrying the microscope to or from your table, grasp it 
firmly by the pillar and hold in an erect position, so that the ocular 
which is fitted loosely into the draw tube may not fall out and its 
lenses become damaged. 
2. Never allow the objective to touch the cover glass or the liquid 
in which the object is mounted. 
3. Never touch the objective or ocular lenses with fingers of cloths. 
4. Never change from lower to higher power objective without 
first ascertaining that the body tube has been raised sufficiently to 
allow the high power objective to be slipped into place without 
injury to the objective or mounts. 
5. Never clean the microscope lenses or stand with cloths that 
have been used for removing surplus of alkali, acid or other reagent 
from slides. 
6. Note whether the front lens of the objective is clean before 
attempting to use it. If soiled, breathe on the lens and gently wipe 
with an old, clean, soft handkerchief or lens paper. If the lens be 
soiled with balsam or some other sticky substance, moisten the 
handkerchief or lens paper with a drop of xylol, taking care to wipe 
it perfectly dry as soon as possible. 
7. Do not let the objective remain long near corrosive liquids, 
such as strong solutions of iodine, corrosive sublimate, or mineral 
acids. Never examine objects lying in such fluids without putting 
on a cover glass. 
8. Never lift the slide from the stage, but, after raising the objec¬ 
tive, slide it off the stage without upward movement. 
9. Never allow the stand (microscope without lenses) to be wetted 
with such substances as alcohol, soap, etc., which dissolve lacquer. 
10. Keep the microscope covered when not in use. 
