CHAP. XXII. HOW TO COLLECT AND PRESERVE INSECTS. 147 



pressly for this purpose, should be used; these are made of 

 different sizes ranging from 1 to 10, the lowest numbers being 

 the finest. The No. 2 pins will ordinarily answer most pur- 

 poses. About one third of the length of the pin should be 

 allowed to project above the insect's back. 



Small insects, one-fourth of an inch in length and under, 

 should be gummed to pieces of card-board or to thin plates of 

 mica, through which the pin is afterwards thrust. These 

 pieces are sometimes cut square, but the better way is to cut 

 one edge into small, wedge-shape teeth, as in Fig. 340. 



Fig. 341. 



Fig. 340. 



For gumming insects upon card-board, etc., Spaulding's 

 liquid glue may be used; or in its stead the following prepara- 

 tion is even to be preferred: 



Pulverized gum tragacanth, three drams; pulverized gum 

 arabic, one dram; corrosive sublimate, one grain; mix and add 

 & little water. 



In order to spread out the wings of butterflies, etc., a setting- 

 board, of some sort should be used; one that is simple in its 

 construction and answers every purpose is shown in Fig. 

 314. It is made of two pieces of soft pine boards (the softer 

 the better) about half an inch thick, one and a half inches 

 wide, and of any convenient length; these should be fastened 

 to upright blocks about one and one half inches high at each 

 nd, and tapering to one and one sixth inches high at the 

 middle. In fastening the two upper pieces to these, leave a 

 space between the upper pieces wide enough to admit the 



