92 EVENINGS AT THE MICROSCOPE. 



may escape through the open trachea of the wings which 

 are cut off. Though he regards these laminae as the cause 

 of humming in bees and flies, he does not decide that other 

 causes may not produce the buzz of cockchafers, &c, in 

 the thoracic spiracles of which he could not discern them.* 



* " Man. of Entom." 468. 



