LOSS OF COLOUR. 



357 



insect, the play of light and colour through the eyes is like 

 that of an opal, supposing the opal to be translucent. Nothing 

 of the kind exists after death. By means of the magnifying 

 glass the multitudinous lenses of the eyes can be seen, but 

 the light, the life, and the glory have departed from them 

 for ever. 



So, in this species, it is just possible in the dried specimen to 

 see that the colour of the body has once been red, though that 

 hue has faded into dusky brown. The upper wings are dark 



Fici. 17a. — Libellula variegata. 

 (Body refl, wings marbled with brown ) 



brown at the base, and tliis colour exists as far as the middle 

 of the wing, the rest being transparent. The lower wings are 

 almost entirely brown, darkening towards the base, and having 

 a few transparent patches. 



There are few insects in which there is so much tendency 

 towards variation as in the Dragon Flies. Even in our own 

 species this peculiarity is very noticeable, but it is especially 

 conspicuous in those which come from other parts of the 

 world. 



The insect which is shown in Fig. 174 affords a good example 

 of variation, as, out of a collection of many specimens, there are 

 scarcely two that are exactly alike. There is one characteristic 



