230 ON INSECT SOUNDS. 



influence liberate the apparatus from that repose which is its 

 natural state, or may set it going simply by change of air current 

 through the thoracic spiracles. Such reflex action may be 

 associated with a passive consciousness, but the insect voice is 

 probably as automatic as its breathing. If the head, wings, legs, 

 and abdomen of a fly be cut off, and the mutilated trunk laid down 

 on a table, its buzz may be heard as long as the thorax breathes ! 



But we too often confound the phjdcal conditions and 

 mechanism of voice with the physiology of vocalisation -, and we 

 are apt to forget that vocalisation (in the act of singing) as well as 

 speech is essentially a series of co-ordinated muscle movements 

 originated in man by psychical motives, and although the human 

 vocal chords are operated upon by an acquired and highly complex 

 automatic function, the whole operation is manifestly directed by 

 the Will. We see this in the selection of notes out of an extended 

 scale, as well as in the power of increasing the number of notes 

 and in modifying their quality and expression. States of conscious- 

 ness are thus associated with articulate speech and vocalisation for 

 which an organ of hearing of corresponding subtlety is as 

 necessary for guidance of the voice as sight is for governing 

 movements of the bod} . But the insect has few notes of unvaried 

 character, and just as the mutilated fly continues to buzz, so the 

 perfect insect ma}'- chirp, croak, and buzz without hearing its own 

 noises, as an artificial toy does. And there is great reason to 

 believe that the greater number of insects are influenced by the 

 vibrations communicated to their bodies in a more direct way than 

 through an organ of hearing -, as indeed our own feeling of 

 vibratory sounds might convince us. And this, if true, would 

 render any organ of speech or distinction of vibratory impressions 

 as sounds unnecessary. 



We may next consider those insect sounds which are not 

 produced by vocal apparatus but which may be musical tones, or 

 mere noises, according to the nature of the mechanism by which 

 they are produced. 



According to the physical definitions of sound, those made by 



