BEETLES THAT "BLUFF" 219 



females is but a natural inference. Some authorities, 

 however, regard this as doubtful, since there are species 

 which appear to lack these stridulating instruments, 

 though possessing ears. But closer observation will 

 probably show that these apparently dumb species are 

 not really so, as Dr. David Sharp, commenting on this 

 fact remarks : " It is well known that sounds inaudible 

 to some human ears are perfectly distinct to others. 

 Tyndall, in his work on Sound, has illustrated this by a 

 fact that is of special interest from our present point of 

 view. * 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 ! ' If human ears are so 

 different in their capacity for perceiving vibrations, it of 

 course becomes more than probable that auditory organs 

 so differently constituted as are those of insects from our 

 own may hear sounds when the best human ear can 

 detect nothing audible. On the whole, therefore, it would 

 appear most probable that the Orthoptera provided with 

 acoustic organs, and which we consider dumb, are not 

 really so, but produce sounds which we cannot hear, and 

 do so in some manner unknown to us. If this be the case, 

 it is probable that these ears are special organs for hearing 

 particular sounds.'* 



Certain of the Grasshoppers of Africa, known to entomo- 

 logists as Pneumorides, have undergone a most extra- 

 ordinary transformation of their bodily shape, as if in 

 response to the demands of these musical performances. 

 They have entirely lost the power of leaping, and the 

 abdomen, in the male, has become transformed into a 

 huge, pellucid, inflated bag or bladder, apparently to serve 



