PRESERVING 191 



labelled. It should stand horizontally until the balsam has 

 hardened. 



Preservation in Life History Boxes. — A most useful prepara- 

 tion illustrating the life history (all stages) of a single species, 

 together with its work, may be made by mounting the 

 specimens in a pasteboard box on cotton under glass 

 (a "Riker mount"). The adult, if wings should show, is 

 spread and dried without pinning. Eggs, larvae (or nymphs) 

 and pupae if hard shelled, are dried; if soft, they are put in 

 small vials of alcohol, and the corks are cut close and covered 

 with sealing wax. Then, with a layer of soft, clean cotton 

 rilling the box, all these specimens are arranged on top of 

 the cotton* and then the glass-topped lid is put on. The lid 

 presses the specimens down into the cotton, where they 

 remain fixed in place. The box is then sealed with adhesive 

 tape and made pest-proof and safe for handling. Such life 

 history exhibits of economic insects are often a good means 

 of conveying very useful information where it is most needed. 



A school collection. — The best kind. of a school collection 

 is one that is made out of local materials by the members of 



the cover: if at the edges, they may be pushed inward by means of a fine 

 wire or a No. insect pin. All the slide mounts called for in the preceding 

 lessons (excepting only the one cross-section of an insect's body) are to 

 be made in this simple way. The ordinary cheap wooden boxes, grooved 

 for holding 25 slides each, are quite satisfactory containers for such prepara- 

 tions. 



* If the specimens are small ancl the box is not rilled by them, enlarged 

 photographs or other pictures may occupy some of the space under the 

 glass. 



