104 THE CAUSES WHICH PROPAGATE 



as to be employed to express the more complex emotions of love 

 and rivalry, causing, at certain seasons, the music to assume the 

 character of a stimulus to reproduction and migration. 



The culminating points of musical perfection in a group are 

 often indicated by other characters expressive of emotion : thus 

 with beetles the Death Watches exhibit love and rivalry in 

 music, and are most sensitive to touch ; or the longhorns pre- 

 dominate in pugnacity. In Lepidoptera music is in direct rela- 

 tion to colour, sound to beauty. Musical Orthoptera and Longi- 

 cornia exhibit pugnacity. This evidently indicates parallel 

 development of the sensorial organs. 



The action of stridulation with a majority of beetles and one 

 of the bee group is a more or less rapid protrusion and contrac- 

 tion of the abdominal segments, a resj)iratory movement which 

 we shall show results from tracheal disposition in Insecta. In 

 some moths and grasshoppers music is implicated with a bladdery 

 inflation of the skin ; but in other insects it is not directly 

 dependent on respiration. With some the action is a sharp nid- 

 nodding, performed by the elevator and depressor muscles of the 

 prothorax or head. Many butterflies and the crickets produce 

 their music by wing friction, resulting from a rapid movement 

 of the extensor and deflexor muscles ; and the grasshoppers to 

 the same end employ the subtile elevator and depressor muscles 

 of their agile leaping legs. 



The music of some crickets, beetles, butterflies, bugs and ants 

 may be synthetically studied by means of the vivarium or 

 aquai'ium ; but that of others, as grasshoppers, must be observed 

 sub (lioo. A box covered with gauze answers well as a cage for 

 Orthoptera ; but beetles that employ their mandibles should be 

 placed under glass or wire gauze. The method here adopted in 

 notating insect music is that of rhythmic syllables composed of 

 consonants and vowels, which may be carried to sufficient perfec- 

 tion to cause grasshopper species individually to respond. Notes 

 produced by musical instruments are also in vogue, bvit these 

 necessitate a technical knowledge, and even then little more 

 than the comparative mellowness, sprightliness, or plaintive 

 nature of the harmonies can be caught. The most acute ear, and 

 that best attuned to agrarian music, notably fails in the task of 

 reproducing its fine quirks and light echoes by means of our 



