OF MICKOSCOPIC OBJECTS. 107 



some days. The turpentine should then be renewed and 

 the eye well washed in it just before it is to be mounted. 

 It may then be set in balsam in the same way as any other 

 object ; but here a difficulty is met with. The eye being 

 spherical upon the surface required, must necessarily be 

 " folded " or broken in attempting to flatten it. This diffi- 

 culty may be often overcome by cutting a number of slits 

 round the edges ; but some object to this mode of treatment, 

 and, where it is practicable, it is much more satisfactory to- 

 mount one in the natural rounded form and another flat. 

 Instead, however, of mounting the organ whole, four or five 

 slides may be procured from each of the larger ones, such aa 

 those of the dragon-fly, &c. 



The antenncB also are often mounted on separate slides, 

 as being better suited for higher powers and more minute 

 examination than when connected with the insect. These 

 two projecting organs, issuing from the head, are jointed, 

 and moveable at will. They differ very much in form 

 amongst the various species, and are well worth the atten- 

 tion of the microscopist. They are usually mounted with 

 the head attached, and perhaps they are more interesting 

 when thus seen. Some few are very opaque ; to prepare 

 these the following method has been advised, though it i& 

 far better to view them as opaque objects : 



Bleach the antennae by soaking in the following solution- 

 for a day or two : 



Hydrochloric acid, 10 drops. 

 Chlorate of potash, ^ drachm. 

 Water, 1 oz. 



This will render them transparent. "Wash well, dry, and 

 mount in Canada balsam. Instead of the above, a weak 

 solution of chloride of lime may be used, by which means 

 the nerves will be well shown. Many, however, are rendered 

 transparent enough bv simply soaking in turpentine for a 

 longer or shorter time. Where the antennas, however, are 

 " Plumose," or feather-like, extreme care is required ia 



