50 PREPARATION AND MOUNTING 



balsam or fluid, as described in other places ; but they are better 

 mounted dry when they are not too opaque. 



Here, too, we may also mention the SEEDS of many plants as 

 most interesting, and some of them very beautiful, objects, requir- 

 ing 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 III. 



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 

 in the sea-water, dried and mounted in cells deep enough to pro- 

 tect them from all danger of pressure, as some of them are exceed- 

 ingly 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 readily removed when handled 

 carelessly, is what is generally called 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. The form of them 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 proportionate length and breadth in different specimens. The 

 markings upon these also vary, some being mostly composed of 

 lines running from the base to the apex, others reminding us of 

 network bead-like spots only are seen in some indeed, almost 

 endless changes are found amongst them. These scales arc not 

 confined to butterflies and moths, nor indeed to the wings of insects. 

 The different gnats supply some most beautiful specimens, not 

 only from the wings, but also from the proboscis, &c. ; whilst 



