Ixiv INTRODUCTION. 



Mr. C. Bourne, on the edge of the second joint of the 

 copulatory apparatus of the male Sjyhcer other ium, an 

 animal allied to Julm. This consists of a chitinous 

 swelling, corrugated by cross-ridges; whilst on the 

 opposite interior surface a rasp-like organ appears, 

 which produces a shrill cricket-like note when rubbed 

 against the aforesaid ridges. 



Correlated auditory organs are in this animal placed 

 in fossae beneath the eyes, and at the base of the 

 antennae.* 



A friend having lent me one of Mr. F. Galton's 

 high-pitch whistles, which are constructed to test and 

 gauge the capacity of the human ear in appreciating 

 acute sounds, I tried its action upon several specimens 

 of Tettigonia viridis. The capacity of this whistle can 

 be regulated so as to produce sounds audible to all; or 

 else, by use of the attached screw, to produce waves of 

 such rapidity, that no human ear can appreciate them. 

 Thus the ear of one person may be distressed by a 

 shrill note; of which another person is at the same 

 time entirely ignorant, — different ears failing at definite 

 pitches. 



Some fifteen experiments were tried on the Tetti- 

 gonia, but all with negative results ; at least the insects 

 did not respond to the chirps of the whistle in such a 

 marked manner, as to lead to the conclusion that they 

 excited them to any action, such as leaping. 



Experiments might be tried with better success on 

 individuals of Cicadetta, or some other genus of the 

 section Stridulantes. 



Smell. 



Probably we have little right to argue from the 

 action of our own special organs of sense to those of 

 insects ; yet as odours must be caused by minute 

 volatile particles diffused through the air, impinging 



* See my observations on the tuberculous di'ums on the antennae of 

 some Aphides (' Monograph of British Aphides,' pub. Eay Society). 



