APPENDIX. 123 



spring. If placed in a warm corner, a few days will be 

 sufficient to dry it thoroughly : afterwards soak it in spirits 

 of turpentine ; the time of immersion to be regulated by the 

 opacity of the object. 



The directions for mounting in balsam are precisely 

 the same as those given for the wings of insects. Care 

 should be taken not to heat the balsam too hot, as it will 

 invariably destroy delicate specimens by curling them up. 

 In tough horny structures, such as the wing-cases of beetles, 

 &c., heat is sometimes an advantage, and there are a few 

 structures that show to advantage when the balsam has been 

 heated to a boiling pitch ; but for the majority of objects, a 

 gentle warmth is all that is required. 



OVIPOSITORS AND STINGS (plate 7, figure 200) are more 

 difficult to prepare, and require some amount of dissection 

 before they can be properly displayed. To do this, some 

 degree of skill is necessary, and a knowledge of insect 

 anatomy, which can be acquired only by study and practice. 

 As a rule, all dissections should be carried on as far as 

 possible with the naked eye ; when this has been accom- 

 plished, we must then seek the aid of lenses. 



The object-glasses of one's Microscope are the best that 

 can be used for the purpose. An inch lens will be found 

 especially fitted for the work. A simple Microscope, pro- 

 vided with a broad stage, and an arm movable by rack and 

 pinion, for carrying the lenses, is the kind of instrument 

 usually employed. It should be strongly made, and capable 

 of bearing a good deal of rough usage. 



Dissections may be carried on under the compound Micro- 

 scope ; but we do not think the beginner would succeed, as 

 objects become inverted and motion reversed when seen 

 through this instrument. If, however, it be provided with 

 an erector, this difficulty is overcome by the object being 

 brought into the same position that it occupies when seen by 

 the n:\ked eye. 



As most dissections are carried on under water, some kind 

 of shallow trough is necessary to contain it : watch-glasses 

 answer the purpose remarkably well. The small white 

 dishes and covers used for rubbing up colours will be found 

 very useful ; also some cork bungs on which to pin the 

 object ; and these last should have their under sides loaded 

 with lead to sink them in fluid. A great many delicate 

 dissections may, however, be made in a drof> of water placed 

 on a slip of glass ; but for all objects of large size, the trough, 

 or some similar contrivance, will be necessary. 



