Symbiosis: a life relationship existing between different kinds of animals or plants, or between animals and plants: true symbiosis is where both parties to the relation benefit: see also parasitism, commensalism. Among the ants social symbiosis exists in its most highly developed form and distinctive terms have been proposed for the various types of relations: Calobiosis, is that association in which one species, often only the female, lives in the nest of and at the expense of another species, either for a time, = temporary - or altogether, = permanent calacobiosis. {Scanner's note: sic} Cleptobiosis, is where one species of ant lives in or near the nest of another, preying upon its larvae or pupae or stealing the food supply. Dulosis, is that mingling of colonies which owes its origin to the enslavement of one species by another. Hamabiosis, is that relation where two species of any insects, one of which may be an ant, live side by side without obvious motive or known advantage to one or both. Lestobiosis, is where the workers of one ant colony "hold up" those of another species and rob them of the food they are carrying to the nest. Parabiosis, is where different species of ants form colonies with inosculating galleries, and have their households strangely intermingled, but not blended. Phylacobiosis, is the relation existing between ants and Termites, the ants living in the doorways of the Termites and functioning as guards. Synclerobiosis, is an association of two species of ants that usually inhabit independent colonies, for purposes that are not clearly understood. Trophibiosis, is the relationship between ants on the one hand and aphids, coccids and the like on the other; these species being sought and attended by the ants for their own benefit: see myrmecophily. Xenobiosis, is where one species of ant lives as a guest in the nest of another, maintaining its own household, and mingling freely with the host species, the two living on terms of mutual toleration. Symbiotic: species that live together in a state of symbiosis. Symmetrical: evenly developed on both sides. Symmetry: that regular arrangement of organs or parts which is capable of division into similar halves or similar radii. Sympathetic nervous system: applied to the nerves and ganglia of the alimentary canal and sonic other viscera which they innervate; = vagus; visceral nervous system. Symphily: the relation borne to ants by the true guests which inhabit their nests and are fed and tended: rendering in return some substance or service desired by the ants: see metochy and synechtry. Symphyla: a group name for apterous species resembling myriapods in appearance, with functional abdominal legs and the genital openings on the last abdominal segment: regarded by some as connecting forms between insects and myriapods, e.g. Scolopendrella.