THE MICROSCOPE. 183 



GENERAL DIRECTIONS FOR MICROSCOPIC WORK. 

 By PROF. E. S. BASTIAN, 



CHICAGO, ILL. 



[From his College Botany, pp. 218-9.] 



1. Acquaint yourself thoroughly with the mechanism of the 

 microscope you are to use. 



2. Observe great care in the removing and putting on of ob- 

 jectives, so as not to drop them, for they are delicately con- 

 structed and liable to injury. The eye-pieces and eyepiece mi- 

 crometer should also be handled with care. 



3. Observe care in focussing, particularly when high powers 

 are used, so as not to run the objective down against the slide 

 and endanger either the cover-glass or the objective itself. Be 

 sure also that you focus the microscope accurately, otherwise 

 the structure of the object will not be distinctly seen. 



4. Give due attention to the adjustment of the reflecting mir- 

 ror, so as to secure the most favorable illumination of the ob- 

 ject. Much of your success in seeing fine details of structure 

 will depend upon the care exercised in this respect. 



5. Bear in mind that many of the reagents used are corrosive 

 and hence should not be brought into contact with the micro- 

 scope. All the acids and iodine reagents will act upon brass 

 work, potassium hydrate will corrode glass, and alcohol will re- 

 move the lacquering from the stand. 



6. All objects examined in liquids should be covered, not 

 only to obviate the danger of injuring the objective, but to avoid 

 the inevitable distortion of the image which a curved or uneven 

 liquid surface produces. 



7. Let cleanliness and care characterize all your work in the 

 microscopical laboratory. Keep all your apparatus, slides, cover 

 glasses, etc., scrupulously clean. Do not touch the glasses of the 

 objectives or eye-pieces with your fingers, for that would be to 

 soil them and impair their optical performance. Whenever 

 they need cleansing, breathe upon the glasses and wipe them 

 either with a piece of perfectly clean and soft linen cloth, or 

 with a piece of the thin, soft paper that is sold at dental supply- 

 stores under the name of Japanese filter paper. A convenient 

 way is to keep always at hand, in a place secure from dust, a 

 quantity of this paper cut into suitable sizes. It is useful, also, 



