Abstract
Seasonal changes in contents of reducing sugars were studied micro-chemically in the main stems of six years old Quercus trees and in their branches grown for rearing wild silkworms. The quantity of the sugars was found muchin the dark, in the pith ray in wood, and in the pith, and it was scanty in the xylem except the pith ray throughout the year. In winter the sugar contents increased greatly in accordance with the decreases of the starch content. The sugars increased in quantity first in the pith and then in the pith ray, and last they were concentrated in the primary cortex in mid-winter. The increase in the sugar contents in winter can be considered as the indication of increasing coldhardiness of the plant. The sugar contents decreased in spring during the budding-time and they showed themselves to be of value generally during the growing season than in winter, showing increases in the time of growth at the maximum rate and decreases in the time of growth at the law rate.
It was worthy of our notice that the contents of both the sugars and the starch decreased obviously in the stems and in the branches in late September, before which the temperature of the air near the ground was higher than that of the underground, after which the former temperature was lower than the latter.
