406 
Argas persicus 
The structure of the wall of the uterus resembles that of the lower 
part of the oviduct, in fact the latter almost appears to be a continuation 
of the former; but, as the sac becomes enormously distended with 
spermatophores, the walls of the body of the uterus are so thinned 
out, that the original character of the epithelial lining is completely 
destroyed. The narrower portion, or neck, of the uterus, being less 
subject to dilation, generally exhibits the normal structure, particularly 
iD the portion near the place of transition from the uterine to the 
vaginal epithelium (see Plate XXVI, fig. 7, ut.). The epithelial lining 
consists of closely-packed elongate columnar cells, with elongated nuclei 
situated at the basal portion of the cells. The muscular layer consists, 
for the most part, of circular and oblique fibres, but the longitudinal 
fibres which form the outer portion of the muscular sheath are not 
collected into separated bands, and are more numerous than those of 
the oviduct. 
The uterus functions as a receptaculum seminis, and though the 
usual number is one or two, we have observed as many as eight 
unruptured spermatophores in the sac at one time; and as the latter 
each measure about 0 8 mm. in length by 06 mm. in breadth, the 
extreme degree of distension, to which the sac is subject, is no matter 
for surprise. 
Sooner or later, the thin membranous envelopes of the spermato¬ 
phores rupture, and the contained spermatozoa are found free within 
the uterus and the lower dilated portion of the oviduct. 
The Vagina. 
The vagina ( vg.,vg '.) comprises that portion of the common genital 
canal which extends from the uterus to the external genital opening, 
and is distinguished from the rest of the genital tract by the fact that 
it is lined throughout with a thin internal sheath of chitin which is 
continuous at the external genital opening with the general cuticle 
of the body. 
In oi’dinary dissections, it is possible, from the external form alone, 
to distinguish two distinct portions of the canal, while sections through 
the part show structural differences of a very marked character. 
The proximal or cervical portion of the vagina (Plate XXVI, figs. 
6, 7, vg.) is a short, stout, cylindrical or barrel-shaped tube, one end of 
which is partially telescoped into the neck of the uterus, generally a 
little towards the ventral side of the latter, while the other end turns 
