306 THE MICROSCOPE. 



In the wings of moths and butterflies we have them also covered 

 with scales or feathers, carefully overlapping each other, as the tiles 

 cover the tops of our houses. The irridescent variety of colouring on 

 the wings arises from the peculiar wavy arrangement of these scales. 

 In Plate X. are seen magnified representations of a few of them. 

 No. 1 is a scale of the Morpho-Menelaus, taken from the side of the 

 wing, of a pale-blue colour : it measures about l-120th of an inch in 

 length, and exhibits a series of longitudinal stripes or lines, between 

 which are disposed cross-lines or stria9, giving it the appearance of 

 brick-work. The microscope should be enabled to make out these 

 markings with the spaces between them clear and distinct, as shown 

 at No. 1 a. 



Polyommatus Argiolus, or Azure-blue, Nos. 2 and 6, are large and 

 small scales taken from the under-side of the wing of this beautiful 

 blue butterfly ; the small scale is covered with a series of spots, and 

 exhibits both longitudinal and transverse striae, which should be most 

 clearly defined, and the spots separated : it is a very good test of the 

 defining power of a quarter-inch object-glass. 



No. 3. Hipparchia Janira, or Common Meadow Brown Butterfly : 

 on this may be seen a number of brown spots of irregular shape and 

 longitudinal striae. Arnici used this as a test-object. 



No. 4. Pontia Brassica, or Cabbage-butterfly, affords an excellent 

 criterion of the penetration and definition of a microscope : it is pro- 

 vided at its free extremity with a brush-like appendage. With a high 

 power, the longitudinal markings appear to be rows of little beads. 



The Tinea Vestianella, or Clothes-moth, possesses very delicate and 

 unique scales : two of these are imperfectly represented near the 

 Acarus found on one of these moths, at page 334. The feathers from 

 the under-side of the wing are the best, requiring some management 

 of illumination to bring out the lines sharp and clear. 



The common clothes-moth generally lays its eggs on the woollen or 

 fur articles it intends to destroy; and when its larva appears, it begins 

 to eat immediately; with the hairs or wool it has gnawed off, it 

 forms a silken case or tube, under the protection of which it devours 

 the substance of the article on which it has fixed its abode. This tube 

 is of parchment-like consistence, and quite white ; it is cylindrical in 

 its shape, and furnished at both ends with a kind of flap, which the 

 insect can raise at pleasure, and crawl out ; or it can project the front 

 part of its body with its fore-feet through the opening, so as to crawl 

 about without removing the rest of its body from the tube, which it 

 drags after it. There are several kinds of clothes-moths ; and the 



