12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'J'J 



sand which is with them, accumulate on the outer edges of the 

 material This can be washed off in the process into a larger recep- 

 tacle below. 



Another method by which rough sorting can be done is by " decant- 

 ing." If the material is shaken up in a tall vessel of some sort, the 

 lighter specimens will stay in suspension for a short period and can be 

 poured off, leaving the heavier ones on the bottom. Successive stages 

 will separate most of the calcareous tests from the sand and the heavier 

 foraminifera. 



One of the most useful methods is that of " floating." The washed 

 material is taken after drying and slightly heated. Then if this heated 

 material is thrown upon cold water those smaller tests, which are 

 filled with air, will float on the surface and can be poured off. In this 

 way beautiful material can be prepared, which is very largely pure 

 foraminiferal tests. This last method combined with " decanting " 

 will give the best results. 



Selecting and mounting. — For the study of material containing 

 foraminifera under the microscope, blackened trays are of great 

 service. These may be made by covering the bottom and sides 

 of a shallow pasteboard tray with India ink. When this is scratched 

 another coat can easily be applied. If one wishes to be more elaborate, 

 an excellent tray can be made by placing a piece of black velvet on 

 the bottom of such a tray and covering it with glass. This gives a 

 very intense dull black surface against which the foraminifera stand 

 out to great advantage. Specimens which are to be studied further, 

 or used for future records, must be mounted in some permanent 

 manner. One of the simplest and best methods for this is a slide made 

 of two pieces of pasteboard, for convenience 3x1 inches, so that 

 they may be used in ordinary slide boxes. The upper card should 

 have a hole punched in the center and securely pasted to the lower 

 one with a piece of black paper inserted below the circular opening. 

 For additional safety a sheath with the top an ordinary glass slide 

 and the base a thin pasteboard, the glass attached to this by two 

 strips of paper at the sides, may be used. In this the slide with the 

 mounted specimens can be placed, and for ordinary examination it is 

 not necessary to remove the specimens. 



In selecting the specimens to be mounted, much the best method 

 is to use a moistened brush. The finest brushes obtainable, 00 size, 

 made of red sable bristles are the best. These make a very fine point 

 indeed, and if touched to a specimen can be used to carry it to the 

 slide. The slides themselves should be covered with a gum made of 



