514 W. H. HARRIS ON THE EMISSION OF MUSICAL NOTES 



sound will cease. For further satisfaction he made the following 

 experiment. He first cut ofl' the wings of one of these flies very- 

 near the base ; but finding that it still continued to buzz as 

 before, he thought that the winglets and poisers, which he 

 remarked were in a constant vibration, might occasion the 

 sound. Upon this, cutting both off, he examined the mutilated 

 fly with a microscope, and found that the remaining fragments 

 of the wings were in constant motion all the time that the buzzing 

 continued ; but that upon pulling them up by the roots all sound 

 ceased." 



Shelver conducted similar experiments, and these go to prove, 

 " with respect to the insects that he examined," that " the 

 winglets are more particularly concerned with the buzzing. 

 Upon cutting off the wings of a fly — but he does not state that 

 he pulled them up by the roots — he found the sound continued. 

 He next cut off the poisers ; the buzzing went on. This 

 experiment was repeated eighteen times with the same result. 

 Lastly, when he took off the winglets, either wholly or partially, 

 the buzzing ceased. This, however, if correct, can only be a 

 cause of this noise in the insects that have winglets. Numbers 

 have them not. He next therefore cut off the poisers of a 

 crane fly [Tipula crocata) and found that it buzzed when it moved 

 the "wing. He cut off half the latter, yet still the sound con- 

 tinued ; but when he had cut off the whole of these organs the 

 sound entirely ceased." 



The only remark that need be made on the experiments of 

 these two observers is, that probably they were made upon 

 different species of flies, and that it is highly probable that 

 the sounds are produced by different methods among the 

 innumerable species of flies that are capable of j)roducing them. 



" Dr. Burmeister, however, was led by his experiments to a 

 different conclusion. Finding that the buzz of a large fly 

 {Eristalis tenax) still continued after the winglets, the poisers, 

 and even the wings had been quite cut off except their very 

 stumps (only in this last case the sound was somewhat weaker 

 and higher), he conceived that the spiracles lying between the 

 meso- and meta-thorax must be the instruments of sound, 

 which accordingly he found to cease entirely when they were 

 stopped with gum, though while the wings wore in vibration. 



" Pursuing his reseaiches, he extracted one of these spiracles. 



