76 THE AMERICAN MONTHLY [Mar 



— Cause: slide not warmed — media having- been shaken 

 up, you cannot handle this too carefully. 



2. — Cover shifting- during- cleaning. — Cause: not dry 

 enoug-h, or too rough handling- ; this media never gets hard 

 like balsam. 



Mounting Foraminifera, Polycistina, or any Small 

 Bodies Dry in Cells. — Cells must vary according to the 

 specimen that is to go into them. It would look very 

 clumsy to see small objects like the above in a very deep 

 cell For general purposes there are nothing better than 

 the tin cells before mentioned. Some are made in vul- 

 canite, but these are very ugly and are never used by pro- 

 fessional mounters. Then we have them in glass, which 

 are very useful for some anatomical specimens. Some 

 have recommended them to be made in card, but these 

 are very unreliable, as they absorb moisture and cause 

 condensation on the inner side of the covering glass. 

 These cells being pure tin, may be used for any known 

 preservative, and are easily put on. Their cost is very 

 low. Our specimen, in this case, we shall have perfectly 

 dry, and in the case of good material clean. Construct 

 your cell and gum the bottom with ordinary gum arabic 

 solution. Place aside to dry. When quite dry, see there 

 js no dust in it. Breathe on the cell so as to make the in- 

 side damp, but from the breath only. Take np the speci- 

 mens and tip a sufficient quantity in to cover the whole 

 bottom. Take the slip in your left hand and gently 

 knock your right hand against it, holding it in a horizon- 

 tal position so as to spread the specimens evenly. Breathe 

 again on it if required. Place it under a low power to 

 see if all the bottom of the cell is covered, as it looks bad 

 to see the ground of the cell in spaces between the objects. 

 When all is satisfactory take a piece of paper, place it on 

 the table, stand the slide on end and gently knock it. Do 

 the same at the side. This will detach any specimens 

 that are not secure enough. Examine again, and if there 



