32 PHYSIOLOGY OF THE HONEY-BEE. 
wings is different in each of the three kinds of inhabitants 
of the hive, and easily recognizable to a practiced ear. The 
hum of the drone is the most sonorous. But worker-bees, 
when angry or frightened, or when they call each other, 
emit different and sharper sounds. On the production of 
these sounds, bee-keepers and entomologists are far from 
being agreed. 
“Inside of every opening of the aerial tubes is a valvular 
muscle, which helps to control the mechanism of respiration. 
This can be opened or closed at will, by the bee, to prevent the 
ingress, or egress, of air. It is by this means that the air is kept 
in the large tracheous bags and decreases the specific gravity of 
the insect. The main resonant organ of the bee is placed in front 
of this stopping muscle, at the entrance of the trachea.” 
“ The humming is not produced solely by the vibrating of the 
wings, as is generally admitted. Chabrier, Burmeister, Lan- 
dois, have discovered in the humming, three different sounds: 
the first, caused by the vibrating of the wings; the second, 
sharper, by the vibration of the rings of the abdomen; the third, 
the most intense and acute, produced by a true vocal] mechanism, 
placed at the orifices of the aerial tubes.”’—(Girard.) 
76. The bee-keeper who understands the language of 
bees, can turn it to his advantage. Here are some ex- 
amples: 
«“ When something seems to irritate the bees, who are in front 
of a hive, on the alighting-board, they emit a short sound, z-z-z-, 
jumping at the same time towards the hive. This is a warning. 
Then they fly and examine the object of their fears, remaining 
sustained by their wings, near the suspected object, and emit- 
ting at the same time, a distinct and prolongedsound. This isa 
sign of great suspicion. If the object moves quickly, or other- 
wise shows hostile intent, the song is changed into a piercing 
ery for help, in a voice whistling with anger. They dash for- 
ward violently and blindly, and try to sting. 
“ When they are quiet and satisfied, their voice is the hum- 
ming of a grave tune; or, if they do not move their wings, an 
allegro murmur. If they are suddenly caught or compressed, 
the sound is one of distress. If a hive is jarred at a time when 
all the bees are quiet, tae mass speedily raise a hum, which 
