48 THE AMERICAN MONTHLY [Feb 



nearly full. Have your specimen soaking for about thirty 

 minutes in a mixture of glycerine and distilled water, 

 about two of the former to one of the latter. Take up 

 the specimen with the forceps. Put it convex side down- 

 wards, just the reverse way to that which you want to 

 show it. Turn it over in the cell. This will expel any air 

 that would get under it. This is easily done with the 

 forceps and a needle point. Now add some glycerine un- 

 til the top is quite convex, examine it under a low power. 

 If all is right, place the cover glass on in same way as 

 directed in former paragraphs on mounting in cells. 

 Gently press down and set aside to dry. When dry, in 

 say twelve hours, carefully wash away with a brush, 

 (either under a running tap or in a small saucer) all ex- 

 cess of glycerine. Set on one side to dry from the water. 

 When all is dry, run an extra ring of cement round the 

 edge of the cover glass. When this is dry again, finish 

 according to taste in the usual way. The directions given 

 will be the same for any fluid mounting. 



Likely Failures. — 1. — Glycerine appearing- full of air 

 bubbles. — Cause : its being shaken up ; glycerine should al- 

 ways be carefully handled, and be allowed to stand in a 

 warm place for two or three days before using. 



2. — Cell appearing to contain a number of little specks of 

 dirt. — Cause : themediamust be filtered occasionally before 

 using. 



3. — One large air bubble, or two small ones appearing in 

 the cell.— Cause: insufficient media in the cell before put- 

 ting on cover glass. 



Quartz Crystals. — Collection of 35 for 70 cents. A. B. 

 Crim, Middleville, N. Y. 



Chinch Bug. — An 82-page Bulletin giving resume of 

 present knowledge by F. M. Webster, is published by the 

 Department of Agriculture for free distribution (1898) . 



For Sale. — A $45 microscope stand for $25. Address : 

 W. A. Murrill, Ithaca, N. Y. 



