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 SEEDS 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 CORALLINES, 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 Algae. (" Micrographic Dictionary," p. 183.) 



THE SCALES OF 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 fiat 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 



