76 SENSE OF HEAKING IN INSECTS. 



water, at the bottom of which was a layer of mud. 

 He dropped a stone on the mud, but the beetles, 

 which were reposing quietly on some weeds, took no 

 notice. He then put a piece of glass on the mud, 

 and dropped the stone on to it, thus making a noise, 

 though the disturbance of the water was the same. 

 The water-boatmen, however, then at once took flight. 

 In face of all the evidence, then, I do not think 

 there can reasonably be any doubt on the subject, and 

 it seems to be clearly established that insects do possess 

 the sense of hearing. 



