408 
A rgas persicus 
papillae which are disposed in transverse rows. Beneath the chitinous 
lining is a layer of small columnar epithelial cells which is thrown into 
regular transverse folds, but, unlike that of the preceding section of the 
vagina, the chitinous lining does not dip between these folds, but 
passes directly over them. 
As already mentioned, the accessory glands ( gl.ac.gen .) open into 
the shallow cul-de-sac formed by the posterior end of the vestibular 
portion of the vagina, immediately above and behind the opening in 
the floor of the latter, through which communication is established 
between the two sections of the vagiua. They consist of a pair of 
sausage-shaped glands which are attached externally to the dorsal 
surface of the vestibular portion of the vagina, immediately anterior 
to the groove which separates the latter from the cervical portion. 
Each gland, which is of the simple tubular type, extends backwards 
for a short distance over the dorsal surface of the uterus (see Plate 
XXVI, fig. 6, gl. ac. gen.). The size of the accessory glands is valuable, 
but the maximum development is attained at the time of oviposition, 
a fact which suggests that their function is concerned in this process. 
The gland is composed of large columnar cells with rounded nuclei and 
a deeply-staining, coarsely granular cytoplasm. The lumen of the gland 
is very small. 
The complexity of the structure of the vagiua in Argas persicus 
finds an explanation, without doubt, in the fact that in addition to its 
ordinary function as a mere channel for the passage of the ova and 
spermatophores, it plays an important part in the process of oviposition. 
Unfortunately, we have never had an opportunity of observing this 
process in Argas, but there is no reason for supposing that it differs 
from the act of oviposition in the Ixodid ticks; and from what we know 
of the latter, we attempt to explain the function of the two parts of the 
vagina as follows: 
The vestibular portion of the vagina during the act of oviposition 
becomes completely evaginated and prolapses through the external 
genital opening in the form of a short ovipositor with a truncated 
extremity. By the contractions of the uterine walls, and also of the 
dorso-ventral body-muscles, the ova are forced, one by one, into the 
contracted anterior portion, or neck, of the uterus, which is only 
sufficiently large to accommodate a single ovum. The cervical portion 
of the vagina then comes into action. The everted lips of the. latter, 
which, as shown above, protrude into the cavity of the uterus, insinuate 
themselves over the ovum, which is maintained in position by the 
