OF MICROSCOPIC OBJECTS. 81 
development is attained, as, if overgrown, they lose much of 
their beauty. Some pollens are naturally so dark that it is 
necessary to mount them in Canada balsam or fluid, as 
described in other places; but they are better mounted dry 
when they are not too opaque. 
Here we may also mention the snnps of many plants as 
most interesting, and some of them very beautiful, objects, 
requiring for the greater part but a low power to show them. 
Most of these are to be mounted dry, as opaque objects, in 
cells suited to them, but some are best seen in balsam, and 
will be mentioned in Chapter IV. 
The CoraLtines, many of which are found on almost every 
coast, afford some very valuable objects for the microscope. 
They must be well washed when first procured, to get rid of 
all the salts of the sea-water, dried and mounted in cells 
deep enough to protect them from all danger of pressure, 
as some of them are exceedingly fragile. The white ivory 
appearance which some of them present is given to them by 
an even covering of carbonate of lime; and should it be 
desired to examine the structure of these more closely, it 
may be accomplished by keeping them for some time in 
vinegar or dilute muriatic acid, which will remove the lime 
and allow of the substance being sliced in the same way as 
other Algz. (“ Micrographic Dictionary,” p. 183.) 
Tue Scares or Insects.—The fine dust upon the wings 
of moths and butterflies, which is so readily removed when 
they are handled carelessly, is what is called the scales. To 
these the wing owes the magnificent colours which so often 
are seen upon it; every particle being what may be termed a 
distinct flat feather. How these are placed (somewhat like 
tiles upon a roof) may be easily seen in the wing of any 
butterfly, a few being removed to aid the investigation. 
Their form is usually that of the battledore with which 
the common game is played, but the handle or base of the 
scale is often short, and the broad part varies in propor- 
tionate length and breadth in different specimens. The 
markings upon these also vary, some being mostly composed 
G 
