Lai'va of Ephemera margiiiata, magnified. The central shaded line represents the gi-cat 

 dorsal channel of the blood. The lateral branched lines the trachetfe. 



CHAPTER III. 



ON THE INTERNAL ANATOMY OF INSECTS. 



Of the Muscles of Insects. ^-Muscle is a substance whicli 

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

 the muscle, which is fleshy ; and the extremities and coat- 

 ing of the muscle, which are tough, strong, and elastic, 

 and are designated as tendon. The surface of muscle is 

 a beautiful microscopic object: it presents a series of 

 exceedingly fine transverse lines, which, in contraction, 

 assume an undulated form. The fibre of muscle is much 



