94 TRUE TALES OF THE INSECTS. 



This Tyndall has illustrated in his work on Sound. 

 " Crossing the Wengern Alp with a friend," he says, 

 " the grass on each side of the path swarmed with 

 insects, which, to me, rent the air with their shrill 

 chirruping. My friend heard nothing of this, the insect 

 world lying beyond his limit of audition." In other 

 words, as Scudder remarks, sounds become inaudible to 

 many persons when they are derived from vibrations 

 more rapid than 25,000 per second, and when the 

 number becomes 38,000, the limit of human perceptibility 

 is reached. This difference in sensitiveness to vibration 

 of human ears, renders it, of course, more probable that 

 ears so unlike our own as are those of insects may 

 be capable of detecting sounds of a shrillness of which 

 the best human ear can hear nothing. We may perhaps 

 then conclude that these Acridiidse with ears, and to all 

 appearances dumb, do really produce sounds, though 

 beyond our range of perception, and do so by some 

 method unknown to us. If this be the case, it is pro- 

 bable that the function of these ears is the hearing of 

 particular sounds. 



Oviposition ; and Philosophy of the Egg-mass. 



The details of the process of oviposition of the 

 Acridiidse are of much interest. The insect has no 



