130 
DRONE ORGANS. 
inside out. The same thing occurs during coition, 
and it is then that the curved spines prevent the with- 
drawal of the organ. Girard says the force which de- 
termines this change is derived from the pressure the 
drone brings to bear upon the sexual apparatus by a 
violent contraction of the abdominal muscles. 
The different parts of the reversed organ appear 
outside one after the other, as far as the bulb, 
and it is then that the spermatophore is discharged. 
The more the abdomen is filled and distended the 
more easily is the organ extruded. When the 
drone flies out the tracheae and sacs are well tilled 
with air, and this considerably increases the pressure 
exercised on the sides of the abdomen. This is 
why coition can only take place on the wing, and 
the upward turning of the organ does not permit it to 
act on insects on the ground. This also explains why 
Huber never saw the accouplement between the drone 
and a virgin queen shut together in a box. In repose, 
the tracheae not being inflated, the pressure would be 
insufficient for that complete reversing of the organ 
which is necessary for the projection of the spermato- 
phore, and for its introduction into the vagina and 
spermatheca of the queen. 
After the expulsion of the spermatophore, the 
drone dies, and the queen returns to the hive with a 
fragment torn from the organ, resembling a filament, 
or white thread, hanging from the vagina — a sign of 
impregnation. What we have just described is not 
only true of drones brought up in the normal cells 
of their sex, the issue of a fertilised mother, but 
