48 



STUDENTS HISTOLOGY 



which are frequently, through accident or carelessness, and often 

 in spite of the utmost care, found mixed with our microscopical 

 specimens. Among the more common objects floating in the air 

 and gaining access to reagents, to subsequently appear in our 

 mounted specimens, are the following : 



Fibers. Procure minute pieces of uncolored linen, cotton, wool, 

 and silk. With a needle in either hand, tease out or separate a few 

 fibers on slides, add a drop of water, and cover.* 



FIG. 25. EXTRANEOUS SUBSTANCES. 



A. Granules of potato starch. 



B. Corn starch. 



C. Wood fibers. The circular dots are peculiar to the tissue of cone-bearing trees. 



D. Spiral thread from a tea leaf. 



E. Fragment of feather. 



F. Cells of yeast and mould. 



Starch. Procure samples of wheat, corn, potato, and arrow-root 

 starch, or scrape materials containing any one of these substances 

 with a sharp knife. To a minute portion on the slide add a drop 

 of water, cover, and examine with L and H. 



Wood Shavings, Feathers, Minnie Insects, Portions of Larger 

 Insects, Pollen, etc., are easily mounted temporarily or permanently, 



These substances, as well as most of those which follow under the same heading, may be 

 mounted permanently as follows: Put the dry material in clean turpentine for a day or two, to 

 remove the contained air. Transfer to the slide, tease, separate, or arrange the elements, after 

 which wipe away the turpentine with strips of blotting-paper. Add a drop of balsam, and place 

 the cover-glass thereon. The weight of the cover will be sufficient to press the object flat, if it be 

 properly teased or separated. 



