616 THE SENSES AND SENSORY ORGANS. 



The only views which appear at all probable are that the 

 halteres are concerned in the functions of equilibration, and 

 that they are possibly connected with the sense of hearing. 



Comparison with the Semicircular Canals of Vertebrates. - - I 

 think it may be concluded, from what is known of the internal 

 ear in Vertebrates, that the functions of the halteres and of the 

 semicircular canals are in some way related to each other. 

 The results of experiments on the semicircular canals of the 

 vertebrate ear, and on the halteres of the Diptera, are in many 

 respects identical. It is well known that in Birds, at least, 

 destruction of the semicircular canals leads to loss of power 

 to maintain equilibrium during flight, and similar results appear 

 in Mammals during rapid movements. 



The existence of chordotonal organs in the halteres, as well 

 as in the recognised tympanic ears of insects, shows that 

 halteres are closely related to the organs of audition. 



Dereham [86], in 1711, 1712, was the first to ascribe the 

 function of balancers to the halteres. 



Robineau-Desvoidy [290], in 1828, was apparently the first 

 who made any experiments on the functions of the halteres. 

 He says that, having heard from some children in a village in 

 Dauphinc that flies from which the balancers had been re- 

 moved cannot fly, he was led to make experiments on the 

 subject. He found that when one balancer is destroyed the 

 insects fly badly, and that when both are removed they cannot 

 fly at all. He adds that removal of the wing-scales, and even 

 perforation of the abdomen, does not affect flight, but that 

 after the removal of the balancers the insects crept away and 

 hid themselves. 



Goureau [291] , in 1843, entirely confirmed Robineau-Des- 

 voidy's statements. 



Jousset de Bellesme [298], in 1878, also came to the con- 

 clusion that the powers of flight are injured by the removal of 

 the balancers, that all power of steering is lost, and that 

 injects so injured fall in a parabolic curve to the earth. 



I . \\Vinlaml [300], in i,s ( ,i, stated that the total loss of the 

 balancers causes the insects to descend very rapidly, and that 



