DRONE ORGANS. 
129 
Below the ridges are situated two membranous 
sacs (e) in the shape of horns, more or less filled with 
air, their openings communicating with the exterior. 
These are the pneumophyses.^ or air vessels {vessies 
ahijlres of Dufour). When sunk they are bent and 
depressed ; but when filled out and well developed 
they become hard and tough, taking the form of 
straight or curved divergent horns. If they are dried 
in this state the membrane preserves its form and 
acquires a papery consistence. 
The spermatophore is pear-shaped, and gives the 
upper part of the organ a bulbous appearance. The 
expulsion of this spermatophore has a curious effect 
on the different parts of the organ, which are thereby 
turned inside out. The organ lies loosely in the cavity 
of the abdomen, and only adheres to the body at the 
edges of the sexual orifice. Girard (48) says it be- 
haves somewhat like the finger of a glove turned 
outside in, which, upon blowing into the glove, filling 
it with air, and then compressing it, will be gradually 
forced out. 
If the termination of the abdomen of the drone 
be examined, it will be found very blunt and slightly 
turned under, so that the orifice is below. By 
well-regulated pressure-* on the internal organs, we 
first force out of this opening and bring into view a 
greyish rounded body iynasque of Reaumur), covered 
with thickly set spines. The pneumophyses {e e) then 
show themselves, unroll, fill out by the introduction 
of air, and the ‘ masque’ is then found in front of their 
bases (to the left in illustration), the organ being turned 
K 
