MUSICIANS 273 



the bee gives expression to her resentment by a 

 continuous angry hum. Burmeister, not content 

 with obtaining information in this way, cut off the 

 wings of bees, and found that they still hummed ; 

 on the other hand, when he closed the openings 

 to the thoracic sounding-box the hum became so 

 feeble as to be scarcely perceptible. John Hunter 

 found that when he held a bee under water the 

 latter vibrated in the immediate neighbourhood of 

 these openings. 



The " buzz " of the Blue-bottle and other two- 

 winged flies is of the same character. Although 

 this sound-box is in communication with the 

 breathing apparatus, it does not appear that the 

 sounds are produced by the passage of air, but by 

 means of muscular movements of the hard matters 

 in the sound-box. 



Perez and Bellesme have distinguished two 

 separate sounds in the hum of a bee a deep note 

 due to the vibration of the wings, and a more 

 acute sound proceeding from the vibration of the 

 walls of the thorax. We have thus an explanation 

 of how insects can hum when their wings are at 

 rest as in an observation by the Rev. J. Hellins 

 on the large yellow-banded fly Sericomyia borealis, 

 which he found at rest among the tors of Dartmoor. 

 He says : " Before long a piping sound was audible, 

 and one of the party said the wind was whistling ; 

 but to this explanation I demurred, having some 

 recollection of having heard the noise before ; so, 

 looking round, I soon saw several large flies resting 

 18 



