PHYSIOLOGY OF INSECTS. 97 



CHAPTER II. 



OF THE ORGANS OF SUPPORT IN GENERAL. 



314. Insects, instead of having internally a 

 frame-work of bones supporting the softer parts, 

 in which are included all the other systems of 

 organs, have their external skin or covering 

 indurated, incrassated, ossified, and invested with 

 the same power as the frame-work of bones in 

 ourselves possesses, of supporting the softer 

 parts, and affording points of attachment for the 

 muscles. 



315. This indurated and incrassated skin com- 

 pletely envelopes the animal in the manner of a 

 suit of armour, inclosing the softer parts, and pro- 

 tecting them from injury : in its composition it 

 possesses most of the elements found in the 

 bones of vertcbrated animals, but not in the 

 same proportions. 



31G. To admit of perfect freedom of motion 

 in the performance of those numerous acts in 



