592 THE SENSES AND SENSORY ORGANS. 
to certain notes, yet he admits that this insect undoubtedly 
hears when the antennz are removed. 
Neither is the anatomical and histological evidence more 
satisfactory. Leydig, Graber, and Hurst have described struc- 
tures which they believed to be auditory. Leydig’s chordo- 
tonal organs in the antennz of Dytiscus are very doubtful. 
Graber describes similar organs in the antennae, palpi, under lip 
and legs of Dytiscus and Telephorus without figuring them. 
Hurst [156] describes and figures a structure in the basal joint 
of the antenna of Culex, and Hammond has shown me some 
very beautiful sections of this organ. Both observers regard it as 
an ear; but, I think, on very insufficient evidence. The scape 
of the antenna is supported by a thin membrane, beneath 
which there are, undoubtedly, very remarkable nerve ter- 
minals. 
This organ is certainly an exceptional one, and it may be 
admitted that the presence of an ear at the base of the anten- 
nule in some Crustacea is an argument in favour of the view of 
Hurst and Hammond. It appears to me more probable, how- 
ever, that the pressure communicated to the tense membrane 
by the action of the air on the great plumose antenna during 
flight would affect this membrane more powerfully than sound 
vibrations, and I think it more probably a balancing organ than 
an auditory organ in the strict sense of the word. I do not 
wish, however, to deny the existence of auditory organs in con- 
nection with the antenna, although I feel that the evidence in 
favour of such organs is far from convincing. The structure in the 
second joint of the antenna of the Blow-fly certainly resembles 
a rudimentary group of chordotonal organs, and perhaps 
indicates the existence of auditory organs in the antenna. I 
have not been able, however, actually to make out chordotonal 
threads, and it appears to me improbable that the antenne are 
organs of audition in insects. 
Experimental Evidence in Favour of an Olfactory Function.— Perris 
[265] gives numerous experiments which led him to the conclu- 
sion that the antenne are olfactory organs, and Hauser [272] 
arrived at the same result. The latter says that neither Silpha 
