174 N. E. McINDOO 
In regard to the buzzing of insects, there are four old views to 
explain how the noise is made, as follows: 1) by the rapid vibra- 
tion of the wings; 2) by the vibration of the thorax; 3) by a special 
modification of the occlusor apparatus in the stigmata, and, 
4) in Diptera, by the vibration of the halteres. Relative to 
Diptera and Hymenoptera, Pemberton (’11) and Aubin (’14) 
show that none of the above views hold good. They determined 
that the buzzing is made by the extreme bases of the wings, as 
is shown for the honey-bee in the present paper. The humming, 
or more common noise produced by the wings, is made by the 
distal portions of the wings. 
We should not expect insects to respond to sounds which have 
no significance to them, nor to sounds not in their category, 
because they may not hear the sounds that we do. The number 
of vibrations perceptible to the average human ear varies from 
32 to 60,000 per second. Now it may be that the insect ear is 
so poorly developed that it can hear only sounds having vibra- 
tions below 32 per second. It may also be that the sense of 
hearing in insects is on no higher plane than that advocated by 
Forel (08), who believes that insects do not hear, at least as we 
do, but compares this perception in them to that in deaf-mutes 
who feel the rolling of a carriage at a distance. 
Bee-keepers are agreed that bees can hear, yet they cannot 
prove it. Von Buttel-Reepen (07), a scientist and an ex- 
perienced bee-keeper, in discussing the behavior of bees has much 
to say about their auditory perception, but still he produces no 
experimental evidence to support his strong statements. 
To obtain material for the structure of the sound-producing 
organ, adult bees were used; but for a study of the so-called 
auditory organs, young bees, nineteen and twenty-one days old 
(counting from the time the eggs were laid) were employed. 
Fresh material was fixed in the modified Carnoy’s fluid and was 
embeded in 60° paraffin. Sections were cut 5 and 8 yu in thick- 
ness, and were usually stained in Ehrlich’s hematoxylin and eosin, 
but a few of them in eosin alone. All the drawings are original 
and were made by the writer at the base of the microscope usually 
with the aid of a camera lucida. 
