[AIR- 7.]

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  1.  Any cell or small cavity filled with air; esp. in pl. a. Small cells in the lungs of animals, forming the extremities of the ultimate ramifications of the bronchial tubes. b. Intercellular spaces or lacunæ in the stems, etc., of plants; air-cavities.

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1787.  Sir J. Hawkins, Johnson, 590 (Jod.). The aircells of the lungs unusually distended.

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1855.  Owen, Skel. & Teeth, 7. An air-cell, or prolongation of the lung,… lines the cavity of the bone.

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1860.  Tyndall, Glac., I. § 7. 56. Compact ice, filled with innumerable air-cells.

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