84. MACALISTER, ON ASCARIS DACTYLURIS. 
structure, which is similar to that described and figured in 
the appendix to Bagge’s ‘ Dissertatio de Evolutione Stron- 
gylus auricularis, and which has been traced by Diesing in 
other Nematodes. Mehlis, in his paper in ‘Isis, 1831, 
p- 81, describes a similar organ as existing in Strongylus 
hypostoma, but imagined he saw it passing as far forward as 
the mouth, in which he thought that it terminated; but this 
error was corrected by Von Siebold; and in many of my 
specimens the character of the external foramen is seen with 
extreme clearness. This undoubtedly is a glandular organ, 
but of what nature it is hard to say. Mehlis (loc. cit.) has put 
forward a not improbable hypothesis regarding its use, and 
imagines that it pours out an irritating secretion, which 
stimulates the wall of the intestine of the host, and so causes 
it to pour out an increased amount of pabulum for the animal’s 
wants : such may be the case, but we have no evidence on the 
subject. 
Enveloping in its convolutions the intestinal canal in the 
female, a tortuous elongated ovarian tube can be traced, 
usually single, though in three of my specimens I found it 
to be double; it commences by a narrow but not very sharp- 
pointed extremity, which is apparently attached slightly to 
the deep surface of the body-wall, near the lower end of the 
cesophagus; from this point it courses tortuously, measuring, 
when extended, twice or three times the length of the entire 
body of the animal. At its commencement it contains a 
finely granular, almost homogeneous, mass, which shortly 
becomes consolidated into oval vitelline masses, which soon, 
at a small and very imperfectly marked dilatation in the tube, 
become perfect ova of a narrow elliptic shape, composed of a 
dark granular, at first obscurely divided, vitellus, which 
occupies one half of the bulk of each ovum, and is surrounded 
by a transparent albuminous fluid enclosed in a hard casing 
or shell. These ova are arranged in a single row in the lower 
or uterine portion of the oviduct, and occasionally from a 
rupture of this tube they may be seen floating free in the body- 
cavity of the parent. 
The perfect ova are not so numerous as they are described 
to be in other species of Ascaris. I have found them to range 
between twelve and fifty-five in number. The uterine tube 
or oviduct terminates at a small and oblique opening on the 
ventral aspect of the animal, and usually at a point midway 
between the stomach and the anus. In case the oviducts be 
double, they coalesce shortly before they arrive at the vulva. 
Siebold refers to this opening as being a transverse slit with 
swollen margins, but it certainly seemed to me to be roundish 
