The induction of vascular differentiation in callus tissue of Phaseolus vulgaris by the application of indol-3yl acetic acid (IAA) and sucrose has been studied by cytological methods. The application of radioactive IAA and sucrose in the induction experiments has enabled the concentration of these substances, which move through the callus tissue mass by simple diffusion, to be estimated.

Various monosaccharides, disaccharides, trisaccharides and sugar derivatives have been used instead of sucrose in order to study the biological role of the sugar molecule in the induction process. The results indicate that sucrose and certain other α-glucosyl disaccharides have a specific action in inducing differentiation into nodules containing xylem, phloem and meristematic activity.

Evidence is also presented to show that possibly only very young cells, immediately following division, can be induced to differentiate.

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