THE MICROSCOPE AND CELL-STRUCTURE. 63 



Great care is necessary in using the high power, since the 

 objective when in focus is so close to the object. Do not let 

 the high objective touch the slide, and above all do not go on 

 ramming or racking the tube down after passing the position 

 of focus, or you may ruin the objective, besides breaking 

 cover-glass and slide and damaging the specimen. Always 

 use a cover-glass with the high objective ; if you cannot see 

 anything clearly, stop at once, move the tube upwards, wipe 

 the objective, remount the specimen (if examined in a drop 

 of water, which is liable to flow over the cover- glass and wet 

 the objective), clean the cover-glass, and start again. 



Keep both eyes open when using the microscope; this 

 lessens the fatigue of microscope work, and is not at all 

 difficult if you practise for a few minutes each time you start 

 work. Accustom yourself to using either eye indifferently. 

 Never work by artificial light if you can help it. 



96. Accessories for Microscope Work. The following appa- 

 ratus is necessary for work with the microscope (Fig. 33) : 



(1) A good razor, slightly hollow-ground or, better, with one side 

 flat, and a strop and hone for sharpening it ; cost of razor, about 

 Is. 6d. 



(2) A few dozen glass slips, 3 ins. X 1 in. (4d. per dozen). 



(3) An ounce of | in. square cover-glasses (No. 2 thickness, 3s. 

 per ounce). 



(4) A pair of fine-pointed forceps (about Is.). 



(5) A scalpel (about Is.) or a sharp pen-knife. 



(6) A pair of fine scissors with sharp points (about Is.). 



(7) A few fine camel-hair brushes (about Id. each). 



(8) A few mounted needles (about Is. 3d. per dozen) ; these can be 

 made by fixing a needle, point outwards, into one end of a pen- 

 holder (Fig 33, D), or a handle adjustable for any needle (Fig. 33, E) 

 can be bought for about 9d. 



(9) A few flat-bottomed watch-glasses (about Is. 6d. per dozen). 



(10) A few ointment-pots with lids, and a few wide-mouthed 

 stoppered or corked glass bottles of different sizes. 



(11) A small spirit lamp (4 oz. size, 9d.). 



(12) Gummed labels, ^ in. square, for naming slides (2d. per 

 hundred). 



(13) A coarse duster, a finer cloth (e.g. an old, but clean, handker- 

 chief), and a small chamois leather. 



(14) Bottle for Canada-balsam or glycerine-jelly, with cap and 

 glass rod (2 oz. size, 8d.). Fig. 33, G. 



(15) Small narrow-mouthed stoppered bottles for the following re- 

 agents ; glass rods are used for bringing drops of the reagents from 

 the bottles to the slide (Fig. 33, H). 



