718 SUMMARY OF CURRENT RESEARCHES RELATING TO 



exactly in its centre. This may readily be done in the following 

 manner : — Take some very finely-powdered Prussian blue and rub it 

 up in a mortar with a little weak mucilage, so as to form a thin blue 

 pigment. A quantity of this should be made so as always to be at 

 hand. A slide having been cleaned, the best surface is to be selected, 

 and on the reverse side, by means of a self-centering turntable, a 

 small circle is to be drawn with a camel's-hair pencil charged with 

 the pigment. In the centre of this ring, but on the opposite side of 

 the slide, the section is to be placed, when it, of course, will occupy 

 a position exactly central. When the slide comes to be finished, the 

 blue ring may easily be removed with a wet cloth. 



Chalk Cells.* — For dry mounting of diatoms, and objects not 

 much exceeding 3L of an inch in thickness, Mr. F. Kitton has been 

 using cells prepared in the following manner : — Wash some whitening 

 in water to get rid of the coarser parts (foraminifera, sponge-spicules, 

 &c), or levigated chalk as sold by druggists can be used, and make a 

 mixture about the consistency of cream with weak gum water ; three 

 or more applications will make cells of a sufficient depth. When dry 

 go over them two or three times with a solution of Canada balsam dis- 

 solved in benzine. The cells should not be used until the balsam is 

 quite hard ; then place the cover (upon which the diatoms ought to be 

 mounted) in position, and with a heated slide press it upon the cell ; 

 when properly attached the cement ring can be made in the usual 

 manner. 



Line and Pattern Mounting.! — Mr. H. Sharp gives the following 

 directions for this kind of mounting, his slides thus prepared being 

 said by Mr. W. H. Wooster to be " exquisite examples of manipulative 

 skill." 



" Requisites : — (1) One or two cat's or mouse's whiskers fastened 

 on match-like sticks or fine rushes, with shellac rather than gum, 

 with about \ inch free. I prefer to have one with the natural point, 

 and another with the point cut back to where it is somewhat stiffer. 

 (2) A good simple Microscope of some kind, either attached to a 

 roomy stage-plate, with a mirror below and revolving plate above, or 

 detached on some stand, but capable of being brought over a mounting 

 table with mirror and rotating plate as above. My own is home- 

 made, extremely simple, costing nothing but the trouble, and such as 

 any one with a little ingenuity could make for himself. It consists 

 of a piece of pine 9 inches long, 5 inches wide, and 1 inch thick, on 

 three legs, with a hole in the centre, into which a wooden matchbox 

 (with the bottom cut out) fits tightly, projecting a little above ; over 

 this fits a piece of slate just tight enough to rotate easily ; beneath, a 

 peg receives the mirror of the Microscope. This forms the detached 

 mounting table. For the simple Microscope, I take the foot and tube 

 pillar of the condenser, fit a piece of cane in this tube, drive a pickle- 

 bottle cork stiffly on it, and fasten on this a horizontal wooden bar 

 with a hole in the middle to fit on the cane, and another at each end 



* Amer. Mon. Micr. Journ., iii. (1882) pp. 151-2. 

 t Journ. Micr. Soc. Victoria, i. (1882) pp, 94-6. 



