NEMATOIDEA. 353 
Ascaris, Lin.(1) 
The Ascarides have a round body, attenuated at each extremity, 
and a mouth furnished with three fleshy papillze, between which an 
extremely short tube occasionally projects. This genus is very nu- 
merous in species which are found in all kinds of animals. Those 
which have been dissected presented a straight intestinal canal, and 
the females, by far the greater number, exhibited an ovary with two 
branches, several times the length of the body, opening externally 
by a single oviduct, near the anterior fourth of the total length of 
the animal. The males have but a single seminal vessel, also much 
longer than the body, which communicates with a (sometimes double) 
penis that protrudes through the anus. The latter opens under the 
extremity of the tail. bs 
Two white threads, one of which extends along the back, and the 
other along the belly, are considered by Messrs Otto and Cloquet as 
the nérvous system of these animals; two other and thicker threads, 
one on the right and the other on the left, are considered by some 
as muscular, and by others as vascular, or even as trachez. 
In some, the head is destitute of lateral membranes. The most 
common species. 3 
Al. lumbricoides, L., is found without any essential difference 
in Man, the Horse, Ass, Zebra, Hemiona, Ox and Hog. It has 
been seen more than fifteen inches in length. Its natural colour 
is white, and it sometimes multiplies excessively, occasioning 
disease and death, particularly in children, or when it ascends 
into the stomach. 
Other species are furnished with a little membrane on each side of 
the head. Such is 
A. vermicularis, L.3; Goetz., V, 1—6; Encyc. Méthod., Vers, 
XXX, pl.x, 1. Very common in children, and in adults afflicted 
with certain diseases, in which it causes an insupportable itch- 
ing at the anus. It is not more than five lines in length, and ‘is 
thickest anteriorly(2). | 
(1) arxapse, the name of the small species that is found in Man, is derived from 
agxapiCw, to leap, to move. 
(2) For the remaining species of Ascarides that infest animals, see Rud., Hist., 
II, 128, et seq. and Synop., p. 37, et seq. 
Vou. IV.—2 U 
