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 
Dauphiné 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 
insects so injured fall in a parabolic curve to the earth. 
E. Weinland [800], in 1891, stated that the total loss of the 
balancers causes the insects to descend very rapidly, and that 
