GENERAL BIOLOGY 



take a cover glass in your left hand, rest one edge of the cover 

 on the slide near the drop, and support the opposite edge on a 

 teasing needle ; lower the cover glass gradually over the drop, being 

 careful to inclose no air bubbles. Do not press upon the cover glass. 



4. Before putting a permanent preparation away label it care- 

 fully with the name of the object and the method of preparation. 



5. Never use reagents haphazard, but only when you have a 

 definite purpose in view. Reagents are used for fixing, hardening, 

 preserving, staining, dehydrating, clearing, embedding and mount- 

 ing. Firing is the process of killing and hardening the living 

 thing so that it preserves as nearly as possible its natural form. 

 Staining is the dyeing of the object so that some parts are more 

 deeply colored than others. Dehydrating is the process of removing 

 the water from the object, usually by alcohol. Clearing usually 

 consists in substituting some oil for the alcohol which is in the 

 object. Embedding is the process of permeating and surounding 

 the object with some substance such as paraffin, preparatory to 

 cutting sections of it. 



6. Miscroscopical slides which have been prepared in this way 

 are valuable, sometimes very valuable, and when such preparations 

 are given out for use they must be handled carefully. Do not crush 

 the cover glass or slide by focusing down on it. Do not pick up your 

 microscope with a slide on the stage, as it is very likely to fall on 

 the floor and be broken. Do not leave slides on the table when 

 you have finished with them but return them to the desk or to 

 the box from which you received them. A charge will be made for 

 every slide that is broken. 



III. NOTES AND DRAWINGS. 



i. Drawings should be made of every object studied; this is 

 necessary not only as a record of what has been seen, but also as 

 an aid to accurate observation. Make your drawings a record of 

 what you actually see and if you cannot see what the directions 

 call for consult an instructor. Do not attempt to make drawings 

 without the object before you and do not make rough sketches 

 and then finish them from memory. In general make outline draw- 

 ings without shading. Where certain structures occur in large num- 

 bers it is sufficient to represent them in only a part of the drawing. 

 Label all important Structures by means of reference lines and 

 marginal words. Use hard pencils (4!!), with very sharp points, 



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