OF MICROSCOPIC 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 as 
- those of the dragon-fly, &c. 
- The antenne 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 is 
far better to view them as opaque objects :— 
Bleach the antenne by soaking in the following solution 
for a day or two :— 
Hydrochloric acid, 10 drops. 
Chlorate of potash, 3 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 by simply soaking in turpentine for a 
longer or shorter time. Where the antenne, however, are 
*‘Plumose,” or feather-like. extreme care is required in 
