132 



THE AMERICAN MONTHLY 



[July, 



from the microscope, and the resuhs 

 we" have seen lead us to believe that 

 it is quite possible to make very good 

 lantern slides from photomicrographs 

 of even such difficult objects as foram- 

 inifera and polycystina. 



On Mounting Diatoms in Lines 

 and Patterns.* 



The following instructions are given 

 by Mr. H. Sharp, who has prepared 

 some beautiful slides : — 



The requisites are : (i.) 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 some- 

 what stiffer. (2.) A good simple mi- 

 croscope of some kind, either attached 

 to a roomy stage-plate, with a mir- 

 ror below and revolving plate above, 

 or detached on some stand, cut capa- 

 ble of being brought over a mounting- 

 table with mirror and rotating plate as 

 above. My own is home-made, ex- 

 tremely simple, costing nothing but 

 the trouble, and such as any one with 

 a little ingenuity could make for him- 

 self. It consists of a piece of pine 9 

 inches long, 5 inches wide, and i 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 re- 

 ceives 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 stifiiy 

 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 in which to fit the lenses, which 

 are just the i^ inch and ^ inch ob- 



*yoiirnal of the Victoria Microscopical 

 Society. 



jectives, which give far better defini- 

 tion than common pocket-lenses. (3.) 

 A steady hand. (4.) Patience and 

 perseverance. 



All diatoms and scales should be 

 mounted on the cover, not the slide. 

 Lay a clean cover on a slide and keep 

 it in place by a drop of water be- 

 tween. As scales are larger than dia- 

 toms, it is well to begin with them. 

 Put several on a slide in the ordinary 

 wa}', pick out the ones wanted with 

 a bristle under the simple microscope, 

 one at a time ; keep the cover flooded 

 with moisture from the breath, and 

 deposit the scales picked up wherever 

 wanted in lines or. patterns. They 

 will readily leave the bristle for the 

 wet glass, and can be pushed about 

 quite easily. When the moisture 

 dries off no stain is left, and the ob- 

 jects will adhere with sufficient firm- 

 ness to resist anything short of a 

 sharp jar. When the line or pattern 

 is finished, mount in a shallow cement 

 cell. 



The cover must have a film of a 

 gelatinous nature which is insoluble 

 in balsam and its solvents. A thin 

 aqueous solution of isinglass carefully 

 filtered serves well. A single drop is 

 placed on a clean cover and spread 

 out as thin as possible with a clean 

 needle. It dries almost instantly in 

 warm weather, and in a few seconds 

 in winter. A diatom placed on this 

 fihn and gently breathed on is securely 

 sealed, and cannot be dislodged with- 

 out moisture. Care must be taken to 

 place the diatom in position while the 

 film is quite dry ; then breathe on it ; 

 allow the film to dry again ; then 

 place another diatom, and so on, till 

 the line or pattern is finished. If any 

 of the diatoms are thick or likely to 

 be crushed, stick three bits of cover- 

 glass under the edge of the cover with 

 gum, and place a dot of gum on each 

 before placing the cover in position 

 on the slide. This, when dry, will 

 keep the cover in its place, while 

 introducing the balsam, before do- 

 ing which, allow a little benzine to 

 run nnder by capillary attraction, 



