CYSTICER'CUS (Gr. bladder-tail), according to many naturalists, a genus of cystic worms (q.v.), characterized by a dilated cyst with a single head, which has four suckers and a circlet of hooks. This genus has, however, latterly been displaced from the system of nature by the discovery that the forms referred to it are only the young of tape-worms. This discovery has been confirmed by a multitude of observations and experiments with regard particularly to C. found in human beings, and in many rodent and pachydermatous animals—as rabbits, pigs, etc.—the young of the common tape-worm; and C. tenuieollis, found more rarely in human beings. but often in the abdominal cavity of ruminant quadrupeds, and of pigs, horses, and many other animals—the young of a of the dog. C. cellulosce often exists in great numbers in the flesh of pigs, causing the diseased appearance known as measly. See
CESTOID WORMS. It sometimes occurs in like manner infesting the human body, in muscles of most various parts; it has been found even in the heart, in the brain, and in the eye. That in such cases it sometimes causes death, is too certain, and its removal is not easy, except when it is so situated that it can be reached by the knife, nor is there any sure indication by which its presence in many situations can be known; but it appears also that it may die and be absorbed without causing any very serious consequences to the person in whom it has dwelt. The cysts of this species are always of small size: those of C. tenuicollis, however, which generally occurs in the liver, or in other abdominal organs, sometimes become, in some of the lower animals, as large as a child's head. Injurious Entozoa.