“…The quiescent centre may be stimulated to divide both when the reproductive future of the dividing cells is damaged as a result of experimental treatments like irradiation (Clowes, 1972), decapitation (Clowes, 1970) or cold (Clowes & Stewart, 1967), and when sucrose starvation produces a decrease in the mitotic rates of the surrounding cells (Rost & Van't Hof, 1973;Webster, 1973). It is particularly noteworthy that ascorbic acid stimulates tbe quiescent centre since this is a compound which is utilized in several metabolic processes (De Leo et al, 1973;Arrigoni, Arrigoni-Liso & Calabrese, 1976, 1977Arrigoni et al, \977h, 1979;Kvidente et al, 1983;Liso et al, 1985).…”