Bud scar-rich preparation, which consisted mostly of crater-like bodies with some fragment of cell wall, was easily obtained from the isolated cell walls of baker's yeast by enzymic treatment under appropriate condition. In spite of low glucosamine content, which is due to the action of chitinase in the enzyme preparation, X-ray diffraction analysis showed that the structure of chitin was well preserved in this preparation.On the other hand, the preparation obtained by chemical treatment of intact yeast cells indicated high glucosamine content.Differing from the results of Bacon et al., the present preparation obtained after 2 cycles of chemical treatment still retained the original cellular shape with remnant cytoplasmic materials. After 5 cycles of the treatment, bud scar-rich fraction nearly equal to that obtained by enzymic treatmet was obtained.By the treatment of the bud scar-rich preparation with chitinase, the characteristic annular structure disappeared with concomitant decrease of glucosamine content, and at the same time, stainability with fluorescent dye, Brightener, of the annular structure disappeared.It was concluded that chitin is the intrinsic entity which constitutes the annular structure of the bud scar region and can be stained with Brightener.The appearance of stainable structures and buds together with the increase in cellular content of glucosamine was observed during culture of age 0 cells. The emergence of buds was preceded by the appearance of the stainable structures ; the increase of glucosamine content proceeded in accordance with the appearance of the annular structure. The morphological basis of the budding was discussed with special reference to the role of the annular structure.Budding yeast cell leaves a bud scar on the surface of mother cell after the daughter cell separated.Attentions were first directed on the conspicuous morphological feature of the bud scar.Many descriptions were made on its morphological structure either on the isolated cell walls or on the ultrathin sections of intact cells ; these are thoroughly described in several reviews (1-4). The number of bud scars of a cell, which corresponds to how many times the cell underwent budding in the past, can be counted by various means. The bud scars can be easily stained with some fluorescent dyes, so that the counting of stained bud scars under fluorescent microscope is the simplest 23

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Experiments were carried out to identify the primary site for aluminium (Al) toxicity in roots. A1 accumulated in large amounts in the younger and outer cells in roots of pea and was retarded when the ionic strength of the A1 solution was high. Cell destruction was extensive in the regions with high A1 accumulation. The accumulation of AI in, and potassium (K) leakage from, the root tip were in the order pea > maize > rice, the same order as their sensitivity to AI.The protoplasts from the root tip portion of pea incubated with AI showed a wrinkled and uneven surface. The protoplasts progressively shrank and eventually collapsed. Viability decreased in this process. In the control protoplasts of maize, ~3-glucan formation was uniform on the spherical surfaces, whereas it was spotty in the Al-treated protoplasts; the cell wall material of the latter contained partly 1, 3-~-glucan which is known to be synthesised by 1, 3-fl-glucan synthase embedded in the plasma membrane. These results suggest that the specific site for AI toxicity is the plasma membrane of younger and outer cells in roots and that AI tolerance depends largely on the integrity of the plasma membrane.

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