GENEKAL SUMMARY. 195 



Mounting and Preserving Cicada. 



More than one method may be employed for pre= 

 serving and stormg these insects. 



The small Tettigidse are very sensible of heat, and 

 they may be killed by a temperature much below that 

 of boiling water. The contents of a sweeping-net may 

 be exposed for a few seconds before the fire of an open 

 grate, and then the specimens may be shaken out on 

 a sheet of white paper, and grouped into genera and 

 species with the aid of a camel-hair pencil. 



For their preservation we may imitate the natural 

 process of enclosure in amber, by the substitution of 

 Canada balsam for the fossil resin. When successfully 

 done, the very small details of the objects will be pre- 

 served for a hundred years or more ; but from the 

 difficulty of examining such objects in all positions, 

 this useful mode must be considered only as a supple- 

 mentary help towards identification. 



Small slips of card, all cut of the same length and 

 each pierced by a smcill pin, will be found convenient 

 in practice. Specimens also may be mounted on 

 pieces of clear mica, but such mountings do not often 

 allow good views of the under sides of the insects. 



Gum tragacanth is almost insoluble in cold water ; 

 but if some fragments be steeped in it for a few hours 

 a transparent jelly or mucilage is formed, which has 

 the useful property of drying into a thin film, without 

 gloss. A small lump of this jelly placed on each 

 strip of card will make a good attachment for any 

 insect which is pressed into it. This plan has the 

 advantage of allowing a subsequent detachment of the 

 object by plunging all into cold water, when the 

 mucilage will swell up as at first. A short pin thrust 

 through the card does not hinder the use of com- 

 paratively short-focussed objectives, which a large pin 

 certainl}?- would do. 



A few drops of a solution in water of mercuric- 



