APPENDIX. 121 



takes place in the mounting. For want of it, many specimens 

 have been spoilt by the intrusion of particles of dust, soot, 

 and other foreign substances. Let the table on which the 

 operator is at work be steady, and placed in a good light, 

 and, if possible, in a room free from intrusion. 



WINGS OF INSECTS. Perhaps these are the easiest objects 

 upon which the beginner can try his "'prentice hand." Here 

 little skill is required. Select a bee, or wasp, and with your 

 fine scissors sever the wing from its body ; wash it with a 

 camel-hair brush in some warm water, and place it between 

 two slips of glass, previously cleaned, which may be pressed 

 together by a letter-clip, or an American clothes-peg ; place 

 it in a warm corner for a few days ; when quite dry, remove 

 it from between the slides, and soak it for a short time in 

 spirits of turpentine. This fluid renders the object more 

 transparent, frees it from air-bubbles, and prepares the way 

 for a readier access of the balsam to the various portions of 

 its structure. 



Having selected from your stock a clean slide of the re- 

 quisite size, and a thin glass cover somewhat larger than the 

 object about to be mounted, hold them both up to the light, 

 when any slight impurities will appear, and may be speedily 

 removed by rubbing the surfaces of the glass with a fine 

 cambric handkerchief, or a piece of soft wash-leather. 

 Should, however, a speck or flaw in the glass itself be 

 found in the centre of the slide, at once reject it and choose 

 another. Remove the wing with a pair of forceps from the 

 turpentine, and place it in the exact centre of the slide : 

 this may be accomplished by cutting a stiff piece of card- 

 board, tin, or zinc, the size of the slide, and punching a 

 hole, the edge of which should be equally distant from each 

 end and each side ; lay the slide upon it, and place the 

 object in the circular space ; you will thus get it properly 

 centred. 



Before dropping the balsam (which should have been 

 previously warmed) upon the specimen, place it under the 

 Microscope : you may possibly detect some foreign substance, 

 in the shape of a particle of soot or a fibre from your hand- 

 kerchief, in contact with it ; remove it with the point of a 

 needle. Take up a small quantity of the balsam on the end 

 of a small glass rod, and let it fall upon the object ; hold the 

 slide for a few minutes over the flame of a candle or spirit- 

 lamp at a distance sufficient to make it warm, but not hot ; 

 the balsam will gradually spread itself over and around the 

 object : should air- bubbles arise, they may be broken by 

 touching them with the point of a needle ; they will, how- 



