Category:Symmetry

Sym"me*try, n. Etym: [l. symmetria, gr. symétrie. See syn-, and meter Rhythm.]

1. A due proportion of the several parts of a body to each other; Adaptation of the form or dimensions of the several parts of a thing To each other; the union and conformity of the members of a work to The whole.

2. (biol.)

Defn: the law of likeness; similarity of structure; regularity in Form and arrangement; orderly and similar distribution of parts, such That an animal may be divided into parts which are structurally Symmetrical.

Note: bilateral symmetry, or two-sidedness, in vertebrates, etc., is That in which the body can be divided into symmetrical halves by a Vertical plane passing through the middle; radial symmetry, as in Echinoderms, is that in which the individual parts are arranged Symmetrically around a central axis; serial symmetry, or zonal Symmetry, as in earthworms, is that in which the segments or Metameres of the body are disposed in a zonal manner one after the Other in a longitudinal axis. This last is sometimes called Metamerism.

3. (bot.) (a) equality in the number of parts of the successive circles in a Flower. (b) likeness in the form and size of floral organs of the same kind; Regularity. Axis of symmetry. (geom.) See under axis. -- respective symmetry, that disposition of parts in which only the Opposite sides are equal to each other.