1897 THE MICROSCOPE. 89 
Eye-pieces land 3, Continental, may be selected. 
Slides.—Two kinds are necessary: the ordinary, for 
mounting specimens ; and the hollow, used for the hang- 
ing drop, Of the former, about one-half gross should be 
purchased, and of the latter about six are required, 
Cover Glasses.—No. I, three-fourths inch square or 
round, may be bought. The squares are the most con- 
venient and less expensive. The principal objection 
usually urged against them is that they are difficult to 
clean without breaking. This I have found not true if 
an ordinary amount of care and not too much pressure is 
used. 
Platinum Wires.——Pieces of No. 24 wire about three 
inches long should be fused to glass rods six or eight 
inches long. Four of them are necessary. 
Plates.—Petri dishes are the most convenient, and six 
or nine will be required for a small laboratory. If Koch 
plates are desired, then, of course, the cooling apparatus, 
benches, moist chambers and sheet-iron sterilizing box 
must also be purchased. 
Very satisfactory Koch plates can be made from 
clear window-glass. Benches may be made by fasten- 
ing small pieces of thick plate-glass to strips of window- 
glass with sealing wax or some other suitable material. 
Sterilizer.—One large Arnold is all that is necessary. 
Incubator.—An ordinary water-jacketed drying oven 
such as chemists use, makes a very satisfactory brood 
oven. Itis, of course, understood that one must have a 
small barner, gas-regulator, and a thermometer, in order 
to complete the apparatus. 
Stain Bottles.—At least six should procured; twelve 
would be better. A very good and economical bottle 
can be made by taking sn ordinary half ounce wide- 
mouth bottle, fitting it with a good tight stopper through 
which has been introduced a straight medicine-dropper. 
