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THE MECHANICAL FUNCTIONS. 



§ 2. Insect a alata. 



Our attention Is now to be directed to the more highly 

 developed Insects, which have been formed with a view to 

 progression through the air. On these, which compose the 

 most extensive class of the whole animal kingdom. Nature 

 has lavished her choicest gifts of animal powers, as far as 

 they are compatible with the diminutive scale to which she 

 has restricted herself in their formation. The model she 

 has chosen for their construction is that which combines the 

 greatest security against injurious impressions from without, 

 with the most extensive powers of locomotion; and which 

 also admits of the fullest exercise of all those faculties of 

 active enjoyment which are characteristic of animal life. She 

 has provided for the first of these objects by enclosing the 

 softer organs in dense and horny coverings, which perform 

 the office of an external skeleton, sustaining and protecting 

 the viscera, and furnishing extensive surfaces of attachment 

 to the muscles, from the action of which all the varied move- 

 ments of the system are derived. 



The muscular system of perfect insects is exceedingly 

 complex. Lyonet has described and delineated an immense 

 number of muscular bands in the caterpillar of the Cossus, 

 and the plates he has given have been copied in a variety 

 of books in illustration of this part of the structure of in- 

 sects. The recent work of Straus Durckheim affords an 



equally striking example of admirable arrangement in the 

 muscles of the Melolontha vulgaris, or cockchaffer, the ana- 



