Source : Webster's Revised Unabridged Dictionary (1913)

Vacuole \Vac"u*ole\, n. [L. vacuus empty: cf. F. vacuole.]
   (Biol.)
   A small air cell, or globular space, in the interior of
   organic cells, either containing air, or a pellucid watery
   liquid, or some special chemical secretions of the cell
   protoplasm.

   {Contractile vacuole}. (Zo["o]l.) See under {Contractile},
      and see Illusts. of {Infusoria}, and {Lobosa}.

   {Food vacuole}. (Zo["o]l.) See under {Food}, and see Illust.
      of {Infusoria}.

Contractile \Con*tract"ile\, a. [Cf. F. contractile.]
   tending to contract; having the power or property of
   contracting, or of shrinking into shorter or smaller
   dimensions; as, the contractile tissues.

         The heart's contractile force.           --H. Brooke.

         Each cilium seems to be composed of contractile
         substance.                               --Hixley.

   {Contractile vacuole} (Zo["o]l.), a pulsating cavity in the
      interior of a protozoan, supposed to be excretory in
      function. There may be one, two, or more.