230 GEO. H. BISHOP 
it has a fairly stiff but elastic chitinized wall, and bears a series 
of complexly modified plates, bristles, and protrusions which 
appear to facilitate its entrance into, and secure its retention 
within, the vagina of the female. ‘The medial portion, the bulb, 
is merely an enlarged and rounded part of this tube; it is on either 
side partially enclosed by a lateral shell-like plate, formed by the 
chitinous thickening of the wall of the bulb. This bulb tapers 
off into the third portion, the ejaculatory duct, a thin-walled, 
elastic, narrow-lumened tube leading to the seminal vesicles and 
the accessory glands (text fig. 1, d and e). . 
In copulation, this apparatus is everted from the drone’s 
body into the vagina of the female. Since the penis itself has 
no muscles attached, its eversion is due to pressure from the 
muscular contraction of the abdominal walls. Starting at the 
region proximal to the genital aperture, the penis is gradually 
forced out from within, as one might force out a glove finger 
that had been turned inside out in stripping off, by blowing into 
the wrist of the glove. The eversion extends, according to 
Zander,’ back to the median bulb, which, acting as a sper- 
matophore, is kept from everting by its two lateral plates above 
mentioned (text fig. 2, B). Schafer’ finds that the bulb also 
everts and concludes that it does not act as a spermatophore, 
but that its size merely enables these lateral plates, whose 
definite function is to hold the penis within the queen’s organs, 
to turn inside out and lodge in their appropriate position like 
the gates of a canal lock (text fig. 2, C). The entrance of the 
ejaculatory duct into the bulb, according to this scheme, is thus 
brought through the everted bulb, and becomes the end of the 
everted penis. Either condition (B or C) may be produced 
artificially by greater or less pressure applied to the drone’s 
abdomen. 
The mesodermal portion of the sexual apparatus (text fig. 1, 
d-h) consists of three elements: 1) Paired testes, at the time of 
emergence of the imago, occupy a large part of the dorsal portion 
of the abdominal cavity; they undergo gradual diminution as the 
sperms are discharged, until at maturity only small triangular 
remnants remain (text fig. 1, g). 2) Passing posteriorly from 
