PHYSIOLOGY OF INSECTS. 133 



CHAPTER VI. 



OF MUSCLES, THE ORGANS OF MOTION. 



494. Next to the external solid parts, which 

 ostensibly perform the active offices of insect life, 

 must be considered those internal softer parts 

 called muscles (museuli) ; the contraction and 

 expansion of which cause the solid parts to per- 

 form those offices. 



495. Muscle is a substance which yields to 

 the touch : it consists of two parts ; the body of 

 the muscle, which is fleshy ; and the extremities 

 and coating of the muscle, which are tough, strong, 

 and elastic, and are designated as tendon. 



496. The surface of muscle is a beautiful mi- 

 croscopic object : it presents a series of exceed- 

 ingly fine transverse lines, which, in contraction, 

 assume an undulated form. The fibre of muscle 

 is much the same in every animal, from man to 

 the most minute animalcule. 



497. The attachment of muscle is solely to 

 the osseous plates or bones, which constitute the 

 external covering of an insect ; in these they 



