184 Additional Note 



' If the net with its captive flies be held to the ear. 

 a distinct buzzing is heard. If a single fly be seized by 

 the legs, so that the wings are free to vibrate, and held 

 close to the ear, the note is plainly heard, and can easily 

 be determined. The male fly yields the note of sharp 

 (about 450 vibrations), the female b (about 240 vibrations). 

 The pitch is not constant, but varies through three or 

 four semitones. No evidence was obtained of any sound 

 other than that due to the vibration of the wings.' 



As different notations are quoted on j)p. 97-9, it may 

 be worth while to explain that Ut 3, Ut 4, and Ut ^ 

 answer to c', c". and c'". 



