A. EARLAND ON FORAMINIFERA. 413 



I will now conclude with a few hints as to working the cleaned 

 material. After being thoroughly dried it should be sifted into 

 various degrees of fineness, and each kept in a separate tube. 

 For examination I prefer a binocular microscope, carrying a nose- 

 piece with 1|" and 1" objectives. The glass stage fixed on Beck's 

 " Economic " microscopes is excellent for this work, as it can be 

 adjusted to move more or less easily, and can be shifted with the 

 left hand, leaving the right hand disengaged for the brush. Also 

 there is no rack and pinion or mechanical movement to get 

 damaged with any scattered sand. A small amount of material 

 should be scattered on the surface of a special slip, made by 

 stretching black ribbed silk over the surface of a piece of card, 

 and surrounding three sides with a wooden ledge in order to 

 prevent the material from slipping off when the microscope is 

 tilted. The ribs of silk should, of course, run across the field, as 

 they serve as ledges against which the foraminifera rest on the 

 slip. I have two or three trays covered with silk of various 

 degrees of coarseness to suit different materials. The foraminifera 

 are easily picked out with a sable brush, which is moistened 

 between the lips and drawn to a point. At the reverse end of 

 the brush handle I mount a short stiff bristle, which is useful for 

 turning over material on the slip. When picked out the forams 

 may either be mounted at once or transferred to a covered cell for 

 future mounting. The best fixative medium is gum tragacanth, 

 which I prefer to gum arabic, as it becomes nearly invisible when 

 dry, and it is also less subject to the influence of those changes in 

 the weather which often cause foraminifera mounted with gum 

 arabic to crack and break. The gum should be made from the 

 finest powdered gum tragacanth, and should be partially dissolved 

 in sufficient spirits of wine to cover the powder. A small crystal 

 of thymol added to the spirit at this stage will sterilise and 

 preserve the mucilage from mould. Distilled water can then be 

 added to dilute it to a proper consistency, which I find to be a 

 very thin jelly, which does not run when the bottle is tilted. The 

 gum need not be used too sparingly in mounting, as it contracts 

 and disappears in drying. 



For mounting foraminifera in balsam, a little of the same gum 

 may be diluted with distilled water until it forms a perfectly clear 

 liquid. A drop of this on the glass slip will be sufficiently strong 

 to hold the foraminifera in position, and at the same time will 



Journ. Q. M. C, Series II., No. 41. 29 



