108 PREPARATION AND MOUNTING 



mounting, though the difficulty is not so great as some seem 

 to think. If they are first dried with gentle pressure, and 

 then subjected to the action of the air-pump in a small 

 quantity of turpentine until the air is thoroughly expelled, 

 they can be easily finished upon the slide, especially when 

 balsam and chloroform are used. 



Insects supply us with another series of beautiful objects, 

 viz., the feet* These are sometimes simply dried and 

 mounted without any medium, as before mentioned; but 

 most of them are rendered much more fit for examination 

 by using balsam in their preservation, as it greatly increases 

 their transparency. The smaller kinds may be dried with 

 gentle pressure betwixt blotting-paper, and then immersed 

 :or some days in turpentine, without requiring the treat- 

 ment with liquor potassae. This immersion will render them 

 beautifully transparent, when they may be mounted in 

 balsam, in the usual manner. 



It is, however, sometimes found difficult to fix the feet 

 when expanded, in which state the interest of the object is 

 greatly increased. Mr. Ralph recommends the following 

 mode : " First wash the feet, while the insect is yet alive, 

 with spirits of wine ; then, holding it by a pair of forceps 

 close to the edge of a clean piece of glass, the insect will 

 lay hold of the upper surface by its foot ; suddenly drop 

 another small piece of glass over it, so as to retain the foot 

 expanded, and cut it off with a pair of scissors, tie up 

 and soak to get rid of air." Mr. Hepworth says that he 

 never found any difficulty in expanding the foot on a 

 drop of water or well-wetted slide, and laying a thin glass 

 oover over it, tying with thread, drying, and immersing in 

 turpentine. 



The mouth, also, with its organs, is an interesting object 

 in many insects. That of the common fly is often used, 

 and is comparatively easy to prepare. By pressing the 

 head, the tongue (as it is commonly termed) will be forced 



* See Mr. Hepworth's interesting articles on the fly's foot in the 

 second and third volumes of the Microscopic Journal. 



