STRUCTURE OF INSECTS. 373 



where necessary, and also softened into pads and suckers 

 where these are required ; as on the feet of those insects 

 which retain their hold upon polished surfaces, and 

 those that are perpendicular or inverted, without the 

 aid of claws. All these, even to the minute hairs with 

 which the bodies of insects are covered as in those 

 that form the fur of the mole cricket, are, without any 

 insertion of new substance, merely elongations of the 

 general covering, by which means the delicate struc- 

 ture of the insect is kept together ; and those that 

 burrow in the earth, or bore into wood or stone, for 

 the purpose of a dwelling for themselves or a nidus 

 for their offspring, never have the most delicate hair 

 even that which requires the assistance of a powerful 

 microscope before it can be seen abraded by the 

 hard substances which they have to encounter. Those 

 which burrow in the mud, too, even though their 

 bodies be furry, seldom have the mud adhering to 

 them ; and those that are smooth have so exquisite a 

 polish, that they are nearly proof against the action 

 of water. We are not aware, indeed, of any surface 

 so perfectly smooth as that of the covering of some 

 insects. This substance, also, admits of every degree 

 of colour and transparency. The horny coats that 

 protect the fixed eyes of insects from external injury, 

 are, in some instances, as colourless as the air itself; 

 while in other parts of them we meet with hues, which 

 not only defy all the imitations of art, but are quite 

 unrivalled among the works of nature. We also meet 

 with an irridescence or play of colours, arising from the 

 light being differently reflected ; but, generally speak- 

 ing, that is mere difference of reflection from the sur- 

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