88 PREPARATION AND MOUNTING 



from them. As they are, howerer, most frequently mounted 

 in balsam or liquid, they will be more fully noticed in other 

 places. 



The scales of fishes are generally mounted dry when 

 used as ordinary objects ; but for polarized light, balsam or 

 liquid must be used, as noticed in Chapter IV. To mount 

 a fish-scale, however, in a satisfactory manner, care must be 

 taken that it is perfectly clean. This can be accomplished 

 only by careful washing, in which process soft camel-hair 

 pencils will often be useful. When the slime or mucus has 

 once dried, it is very difficult to remove. The variety and 

 beauty of these are quite surprising to the novice. It is 

 also very interesting to procure the skin of the fish when 

 possible, and mount it on a separate slide to show how the 

 scales are arranged. The sole is one of the most unusual 

 forms, the projecting end of each scale being covered with 

 spines, which radiate from a common centre, while those at 

 the extremity are carried out somewhat resembling the rays 

 of a star. One of the skates has a spine projecting from the 

 centre of each scale, which is a very curious opaque object, 

 especially when the skin is mounted in the manner described. 

 The perch, roach, minnow, and others of the common fishes 

 give the student good objects for his cabinet, and may be 

 procured without difficulty. The scale of the turbot is a 

 splendid object for the polariscope when mounted in balsam. 



Insects which are very transparent, or have the " metallic 

 lustre" with which any medium would interfere, are mounted 

 dry. The diamond -beetle, before mentioned, is a splendid 

 example of this ; the back is generally used, but the logs, 

 showing the curious feet, are very interesting objects. In- 

 deed, amongst the legs and feet of insects there is a wide 

 field of interest. When they are of a horny nature, it is 

 best to dry them in any form preferred, but to use no 

 pressure; when, however, they are wanted flat, so as to 

 show the feet, &c., extended, they must be dried with a 

 gentle pressure betwixt blotting-paper if possible. But this 

 will be treated more fully in Chapter IY. 



