# 1911 Encyclopædia Britannica/Worm

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​WORM, a term used popularly to denote almost any kind of elongated, apparently limbless creature, from a lizard, like the blind worm, to the grub of an insect or an earthworm. Linnaeus applied the Latin term Vermes to the modern zoological divisions Mollusca, Coelentera, Protozoa, Tunicala, Echinoderma (qq.v.), as well as to those forms which more modern zoologists have recognized as worms. As a matter of convenience the term Vermes or Vermidea is still employed, for instance in the International Catalogue of Zoological Literature and the Zoological Record, to cover a number of wormlike animals. In systematic zoology, however, the use of a division Vermes has been abandoned, as it is now recognized that many of the animals that even a zoologist would describe as worms belong to different divisions of the animal kingdom. The so-called flatworms (Platyelmia, q.v.), including the Planarians (q.v.). Flukes (see Trematodes), Cestodes (see Tapeworm) and the curious Mesozoa (q.v.), are no doubt related. The marine Nemertine worms (see Nemertina) are isolated. The thick-skinned round worms, such as the common horse-worm and the thread worms (see Nematoda), together with the Nematomorpha (q.v.), Chaetosomatida (q.v.), Desmoscolecida (q.v.) and Acanthocephala (q.v.), form a fairly natural group. The Rotifera (q.v.), with probably the Kinorhyncha (q.v.) and Gastrotricha (q.v.), are again isolated. The remaining worms are probably all coelomate animals. There is a definite Annelid group (see Annelida), including the Archiannelida, the bristleworms (see Chaetopoda), of which the earthworm (q.v.) is the most familiar type, the Myzostomida (q.v.), Hirudinea (see Leech) and the armed Gephyreans (see Echiuroidea). The unarmed Gephyreans (see Gephyrea) are now separated from their former associates and divided into two groups of little affinity, the Sipunculoidea and the Priapuloidea (qq.v.) . The Phoronidea (q.v.) are now associated with Hemichordata (q.v.) in the line of vertebrate ancestry, whilst the Chaetognatha (q.v.) remain in solitary isolation.
Mention is made under Tapeworm of the worms of that species inhabiting the human body as parasites, and it will be convenient here to mention other parasitic varieties. The most common human parasite is the Ascaris lumbricoides or round worm, found chiefly in children and occupying the upper portion of the intestine. They are usually few in number, but occasionally occur in such large numbers that they cause intestinal obstruction. Unlike the tapeworm no intermediate host is required for the development of this worm. It develops from direct ingestion of the larvae. Various symptoms, such as diarrhoea, anaemia, intermittent fever, restlessness, irritability and convulsions are attributed to these worms. The treatment is the administration of santonin, followed by a purgative. The thread worm or Oxyuris vermicularis is a common parasite infecting the rectum. The larvae of this worm are also directly swallowed, and infection probably takes place through water, or possibly through lettuces and watercress. The symptoms caused by thread worms are loss of appetite, anaemia and intense irritation and itching. The treatment consists in the use of enemata containing quassia, carbolic acid, vinegar or turpentine or even common salt. In addition mild purgatives should he given.