AS'CARIS (Gk. daxanic, as•a•is, a worm in the intestines). A genus of intestinal nematode worms, which are of comparatively large size. The body is thick, and the mouth is usually sur rounded with three lips or cephalic valves, one in a dorsal position and the other two in the median neutral line. Species of Asea•is are found parasitic in man, pigs, sheep, calves, horses, dogs, eats, etc. The members of the species arc commonly known as stomach worms. Their presence in the intestines of animals does not cause pronounced symptoms of disease unless the worms occur in large numbers. They may then produce reflex nervous disturbances and epileptic attacks. Since these worms are not attached by means of hooks or otherwise to the walls of the intestines, they may be expelled by the administration of cathartics and vermifuges in liberal quantities. The best-known species is the round-wo•m (q.v.), the equally well-known pin-worm (q.v.) being placed in a closely allied genus. Another species (.1 sea nix m egoloce
phalli), much larger than the preceding, is found in the intestine of the horse. It is some times as large around as a lead pencil, and has a noticeably large head. it is of especial interest to biologists, because it was upon the eggs of this species that the German scientist Boveri made his notable observations regarding cell division and the behavior of the chromosomes. Another interesting species (Asearis nigrorenosa) is found in the lungs of frogs and toads, where it is a hermaphrodite; but from its fertilized eggs unisexual worms arise, which live in damp, muddy earth. The females are viviparous, but give birth to not more than four young, which find their way into a frog or toad and there grow into the adult hermaphroditic form, thus com pleting the cycle. For an account. of these worms in the human body, see Worsts.