Contractile vacuole

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.
   [1913 Webster]

   {Contractile vacuole}. (Zool.) See under {Contractile}, and
      see Illusts. of {Infusoria}, and {Lobosa}.

   {Food vacuole}. (Zool.) See under {Food}, and see Illust. of
      {Infusoria}.
      [1913 Webster]
    

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.
   [1913 Webster]

         The heart's contractile force.           --H. Brooke.
   [1913 Webster]

         Each cilium seems to be composed of contractile
         substance.                               --Hixley.
   [1913 Webster]

   {Contractile vacuole} (Zool.), a pulsating cavity in the
      interior of a protozoan, supposed to be excretory in
      function. There may be one, two, or more.
      [1913 Webster]