THE PRESERVATION OF SPECIMENS. 305 



for holding the wings down while they are being ar- 

 ranged. This is made of a large, sharp-pointed pin 

 (usually a black pin) and a piece of 'wire 

 (Fig. 273). Fig. 272, c, illustrates the way 

 in which these spreading pins are used. 

 Only two of these are needed, as they are 

 removed after the broad strips of paper or 

 mica are pinned over the wings. 



No rule as to the position in which the 



wings should be placed can be made that Fig. 273-— a 

 will apply to all specimens. But usually ^^^ '"^ ^*"' 

 in spreading moths the fore wings are t>rought so far 

 forward that the hind edges (the inner margins) of 

 the two wings form a straight line across the insect 

 at right angles to the direction of the body, and the 

 hind wings are brought forward so that their front 

 edges (the costal margins) are nearly covered by the 

 fore wings. Great care should be taken to have the 

 wings of the two sides in similar positions. 



Relaxing Insects. — It is often desirable to 

 spread insects which have become dry ; this is espe- 

 cially the case where butterflies are put into envelopes 

 when collected, or where more moths are collected 

 and pinned than can be spread at once. Such speci- 

 mens can be spread at any time later by first relaxing 

 them. To do this partly fill a vessel with sand and 

 saturate the sand with water ; lay the specimens to 

 be relaxed upon a piece of paper spread over this 

 sand, and tightly close the vessel. If a damp towel 

 be spread over the top of the vessel before the cover 

 is put on, the air in the vessel will be more surely 

 kept moist. After the specimens are left for a time — 

 from one to three days — in this moist atmosphere, 



