DEVELOPMENT OE THE OVARIES IN THE BLOWFLY. 433 
stand how this duct has been overlooked, or how it has been 
supposed that the glands open into or with the seminiferous 
capsules. The gum-glands have also probably been confounded 
with true vaginal glands, which appear to exist in some insects. 
I shall again refer to the gum-glands in a special section of 
the present paper in relation to their structure and functions. 
The uterus (figs. 1, 2, 3, ut .) is a thick-walled sac lined by a 
strong cuticular membrane, very different to the thin cuticular 
membrane lining the oviduct. It has a diverticulum or pouch 
(p) on its dorsal wall immediately behind the orifice of the 
common oviduct. This pouch ( sacculus , figs. 1, 2, and 3, p ) 
is lined by a very thick laminated cuticle with a projecting 
median ridge which appears to divide it into two lateral pockets. 
Each of these pockets opens behind into the uterus, and is 
usually filled with a clear colloid mass, which stains very deeply 
with alkaline carmine. It has all the appearance of being the 
same material as that which cements the eggs together when 
they have been deposited. The same contraction of the uterus 
which expels the egg would certainly expel some of this material 
from the uterine pouch. 
4. The Structure of the Gum-glands . 
Although I have used the term gum-glands to designate 
these organs, it will be seen that there is nothing in their 
structure to justify its use. And although they are usually 
regarded as secretin g-glands which form a glue or cement for 
the attachment of the eggs, a function first apparently ascribed 
to them by Burmeister (7) and afterwards by Loew (18), Stein, 
who has examined these structures with more care perhaps than 
any other writer, entirely discards the view. He regards the 
so-called gum -glands as accessory organs of fertilization except 
in the Hydrophiiidse, where they open into the calyx of the 
ovary ; and, curiously enough, disregarding the extreme impro- 
bability that gum-glands would open in such a situation, makes 
an exception in these insects, and regards the glands as gum- 
glands. Stein further identifies these glands in the Diptera 
with his “ glandular portion of the organs of fertilization.” 
