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ANATOMY AND PHYSIOLOGY 
coating to the eggs before they are extruded. This 
varnish, however, is more commonly imparted to 
them in the wider part of the duct, formed by the 
union of the tubes from the two branches of the 
ovaries. This common duct is sometimes called the 
egg-canal. It is of greater diameter than the ovi- 
duct and frequently distended in the middle where 
the egg occasionally remains stationary for a time 
before being expelled. Of the various appendages 
of this portion of the egg-conduit, the most import- 
ant are the sperm-reservoir, ( Spermatheca ) gluten 
secretors, and the poison vessels of the aculeate 
Hymenoptera. The former is a purse-shaped ap- 
pendage or distention of the duct, destined for the 
reception of the male influence during copulation, 
and, according to Herold, the eggs are impregnated 
in passing it, for it is situate on the upper side, and 
whenever it opens the sperm flows into the duct. 
The gluten secretors are commonly more slender, 
and of a vascular structure, performing the office of 
a gland. The liquid they secrete is white, and it 
envelopes the eggs in their passage. Their situation 
is very close to the sperm reservoir. The poison 
vessel of the Hymenoptera is an ovate bladder with 
a narrow duct appended to it, which discharges the 
contents into the sting. 
The vagina is simply the terminating portion of 
the evacuating duct ; a short straight tube, generally 
a little narrower than the common branch of the 
oviduct. When an ovipositor exists, the vaginal 
tube opens directly into it, forming a continuous 
