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Intact stem apices of Lilium longiflorum Thunb. cv. ‘Ace’ were prepared for scanning electron microscopy to determine floral initiation and differentiation by viewing topographical changes. The apices, after removal of leaves under running water, were frozen in liquid N2, freeze-dried on carbon discs and coated with carbon prior to viewing. Electron photomicrographs were taken of vegetative, transitional and reproductive apices. This method of tissue preparation permitted microscopic evidence of flower bud initiation and differentiation to be obtained in less than 9 hr after removal of the apex from the plant. The apices retained their in vivo configuration, but as dry, permanent, 3-dimensional mounts. Cell net studies of the apical meristem are possible with this technique. This method of preparation is also adaptable to light microscopy.

Single crystals and clusters of crystals or druses found by polarized light microscopy in tissues of Pyrus malus L. cv. Jonathan were found to contain Ca using the electron microprobe. Crystals insoluble in 20% acetic acid occurred in cells adjacent to the vascular tissues near the pedicel in mature fruit and in dormant flower buds, stems, petioles, shoot apex, roots and callus tissue. Because of deposition of calcium as crystals, calcium supplies to cortical cells of apple fruit may be limited and may result in an increased incidence of internal breakdown due to low Ca levels in those cells.

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