

WINGS OF INSECTS, AND THEIR CLASSIFICATION. 5 1 



Yet what is the painting upon these beautiful wings, 

 and by what means are the gem-like colours obtained ? 

 Let us look into the composition of this common and 

 doubtless very simple little object a butterfly's wing. 



The wing here, as in other tribes, consists of two fine 

 membranes, between which lie the " nervures," a series 

 of tubes, on the nature of which philosophers are hardly 

 yet agreed. Nevertheless, be they veins, or air-tubes, or 

 whatever they may be, it is certain that they perform 

 the mechanical office of bones, in strengthening and 

 supporting the wing. 



Attached to the membranes, on both sides of the 

 wings, are innumerable minute scales (the dust), each 

 having a little stalk inserted in the membrane of the 

 wing, and all being arranged like tiles, in regular rows, 

 one overlapping another. The variety of form in these 

 scales is very great even in the different parts of each 

 individual ; but a distinctive form of scale, generally con- 

 fined to the male, is found in some genera and species. 

 Some scales are oblong, others triangular, others heart- 

 shaped and tasselled, others in the form of a battledore. 



The structure of these scales is next to be observed, 

 and it will be seen that they are not quite so simple as 

 we might have expected, if we believed as of course we 

 ought to believe all the instructive little books that 

 talk to us about the " simplicity of nature." 



Each of these scales is found to consist of two or 

 three layers of fine membrane. In some the upper layer 

 is more or less covered with granules of colouring 

 matter ; in others the second layer is covered with parallel 

 lines, apparently composed of these granules ; while in 

 others the second and third layers have the power of re- 

 flecting the most brilliant prismatic colouring. By some 

 E '4 



