Abstract
In this paper it is reported that the distribution of oil glands of the leaves and the state of accumulation of the oil drops in the oil glands before and after the coming out of spikes of Perilla species and the cause of lowering of the percentage of oil after the coming out of spikes. 1) The number of oil glands per unit area of the leaves significantly decreases in the direction from the first leaf in the top portion to the 8th leaf with the growth of leaves, which shows a tendency similar to the variation in the rate of oil yield. 2) As a result of the examination of the distribution of oil glands on the whole rear surface of the leaf it has been found that the top portion of the leaf is less in the distribution of oil glands and the neighborhood of the midrib of the basal portion of the leaf is high in the distribution. This tendency is especially significant in young leaves. 3) As the cause of lowering of the rate of oil yield after the coming out of spikes in comparison with that before the coming out of spikes, the distribution density of oil glands (crown portion of each oil gland has formed a cup-like shape) which has small amount of accumulated essential oil may be counted. 4) Since the central portion of oil gland recesses and each forms a cup-like oil gland, in is considered that the essential oil accumulated in the cup-like oil gland has decreased. Judging from the fact that the oil drop in the cup-form oil gland is not dyed red even if it is dyed by sudan IV, it may also be considered that the lowering of the rate of oil yield is due to the change in property of the essential oil.
