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Short, needle-shaped calcium oxalate crystals have been observed in the fusiform cells throughout the cambial zone in the bark of Gmelina arborea Roxb., a deciduous tree in western India. They are similar to the crystals found in ray cells of the cambium and in axial and ray parenchyma cells in the secondary phloem of this tree. The crystals are most abundant when the cambium is inactive. During the period of meristernatic activity there is an overall reduction in their density in the bark, particularly in the inner bark where fusiform cambial cells and axial parenchyma cells in the conducting zone of phloem appear practically free of any crystals. However, ray initials and their derivatives in the phloem possess some crystals at all times. The occurrence of calcium oxalate deposits in a meristem and the reversible nature of these deposits support the view that they represent areserve of calcium rather than a waste product.

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