402 
A vgas persicus 
is very thin, the response to the stimulus of light is more active than in 
the mature stages when the cuticle is thicker and less transparent 1 . 
For detailed information on the sensory perceptions of this tick, the 
reader is referred to the excellent paper cited above. 
The Genital Organs. 
Plates XXVI-XXVIII (see also Part II, Plates XIV-XVI). 
The genital organs of Argas persicus, as is the case in the ticks as a 
whole, are situated in the middle part of the body, between the alimen¬ 
tary canal and the ventral body wall. The gonad— ovary or testis as 
the Case may be—is an unpaired organ which lies transversely across 
the posterior half of the body, just in front of the auterior limit of the 
posterior-median dorso-ventral body-muscles; from each lateral extremity 
an efferent canal— oviduct or vas deferens —takes its origin and after a 
somewhat tortuous course this canal opens, together with its partner of 
the opposite side, into a common median receptacle, the uterus in the 
female and the seminal vesicle in the male. From the median receptacle, 
a short canal leads directly forwards to the external genital orifice. In 
both sexes, certain accessory glands are associated with the terminal 
unpaired section of the genital tract, these glands in the case of the male 
assuming an extraordinary degree of complexity. 
From the foregoing general account, it is seen that the genitalia of 
this tick agree, in the essentials of their form and arrangement, with the 
sexual organs of other ticks, and indeed, so far as present knowledge 
extends, with those of the Acarina generally. 
No separate receptaculum seminis is developed in the female, as we 
know to be the case in some, if not all, of the Ixodidne. 
In common with all the Ixodoidea, Argas persicus is oviparous and 
the spermatozoa are extruded in the form of spermatophores. No 
special intromittent organ is developed in the male, the spermatophore 
being introduced into the female genital canal by the capitulum of 
the male. 
The genital organs apparently attain their complete development, so 
far as the various parts are concerned, in the deuteronymph, though, of 
course, the sexual glands are then immature and the opening to the 
exterior is not patent 
The subsequent changes are by no means easy to follow, and in the 
following pages we shall confine ourselves principally to a description of 
1 Hindle, E. and Merriman, G. (1912), p. 206. 
