224 ON INSECT SOUNDS. 



imitative effort as in a parrot, but simultaneously with the 

 development of the ideas of which words are arbitrary signs. And 

 we know too, that an insect's voice undergoes no evolution in 

 dependence upon its experience with external surrounding, but 

 remains what it was from the beginning to the end of its life. 



Observation also teaches us that a truly wonderful inter- 

 communication is effected between insects by a subtle development 

 of the tactile organs and the sense of touch, compared with which 

 the sense of hearing is so obscure, that the existence of an organ 

 of hearing in insects has been doubted by many naturalists, and 

 discovered only recently in a few insects. It is further clear that 

 for the perception of the monotone insect voice no complex organ 

 of hearing is needed. And it is difficult to believe that a sound 

 void of all inflection, and taken up by an organ incapable of 

 receiving any varied modulation, can express much spontaneity of 

 motive in an insect, or convey to its fellow insect the various 

 emotional impressions which we distinguish by the words alarm, 

 joy, anger, pleasure, command, and so forth.. In the sequel of 

 this paper some recent experiments and observations bearing upon 

 this subject will be detailed. 



It is impossible to accept the popular belief in the emotional 

 significance of insect sounds, without at the same time admitting 

 that such exercise of vocal function stretches far beyond any yet 



nerve, which must therefore be a local sense organ : for without local organic 

 sensibility of the nerve end there could be no transmission to the ganglionic 

 centre. The excitation of this ganglionic centre may vary in quality or 

 quantity, according to the disposition of the peripheral end of the afferent 

 nerve in the skin, mucous membrane, gland, parenchyme of viscera, &c., or 

 according to some differential character of the nerve end. But the reflex acts 

 following excitation of the same sensory fibre may be of the most varied kind, 

 depending, perhaps, on the discharging power of the ganglionic centre under 

 varying nature and intensity of excitation. Yet there is not only entire 

 absence of consciousness on the part of the individual, but every reflex 

 movement can be as readily produced in a decapitated insect, or any other 

 animal, as in the uninjured animal. 



