THE MOSQUITO 71 



described, for it is next and nighest the 

 insertion of the wing into the body. But 

 Dr. Nuttall found that when this short 

 stump was removed all perceptible sound 

 ceased, which is certainly an argument in 

 favour of these rods and bars playing some 

 part in the production of the buzzing, and 

 in opposition to the view of Howard and 

 others that the buzzing is caused by certain 

 chitinous structures in the tracheae. 



M. J. Perez ^ has carefully gone into the 

 question of the production of sound in the 

 Diptera. He claims to have shown experi- 

 mentally that the stigmata take no part in 

 the production of sound. ' Les causes du 

 bourdonnement resident certainement dans 

 les ailes.' He, too, points out that if the 

 wings are cut short the notes become more 

 acute, until the timbre resembles that of certain 

 interruptors which break and make an electric 

 conductor. This sound we should attribute to 

 the stridulator described above. M. Perez de- 

 finitely states that both in the Diptera and in 

 the Hymenoptera the buzzing is due to two 

 causes : ' L'une, les vibrations dont I'articula- 

 tion de I'aile est le siege et qui constituent 

 le vrai bourdonnement ; I'autre, le frotte- 

 ment des ailes contre Fair, effet qui modifie 

 plus ou moins le premier.' The apparatus we 



1 Compt. Bend. Acad. Paris (1878), Ixxxvii, p. 378. 



