Studies on the Elongation of Petioles in Some Dicotyledons (The First Report)

1. If we divide the young petiole into certain zones with equal intervals, each zone elongates to a different extent; the result may be summerized in three types:Type a, in which each zone in the petiole elongates nearly equally.Type b, in which the upper zone of the petiole shows a conspicuous elongation.Type c, in which the lower zone of the petiole shows a conspicuous elongation.2. It is assumed that in type a, there is no important influence of the meristematic part upon the elongation of the petiole, but in types b and c, the petiole elongates itself through the influence of the meristematic part situated in the uppermost zone of the petiole.3. Among these three types, typeb is the most common, in which their elongation ceases from the lowest zone upwards.4. The energy of elongation is least in the lowest zone in each type.5. In a full-grown petiole, even if the uppermost zone shows the maximum elongation, the zone does not always show the maximum elongation among divided zones through the whole growing period; on the contrary, at a certain period in the course of the elongation other zones also show the maximum elongation.