Abstract
The contents of starch grains in the main stems and branches of six years old Quercus trees, the feed of wild silkworm, were studied histochemically throughout a year at Ariakedistrict, Naganoken, Japan. The result obtained were as follows:
1) Seasonal changes in the contents of starch grains throughout a year are the samein stems and branches in spite of their ages. The mode of change in starch contents inthe terminal of each stem and branch was more obvious than that in the proximal ends.
2) There were two periods which showed the maximum values of starch contents ineach part of them; the one was in just before shooting and the other is in that of autumunalcoloring of the leaves. They were more obvious in the latter period than in the former.There were also two periods of the minimum values of starch contents; the one was inthat of rapid growing of shoots and the other is in mid-winter. In the former period, almostall of the starch grains in the wood disappeared, while in the latter period, almost all ofthem in the bark and wood were lost.
3) The increase of fat contents in accordance with the decrease of starch in wintercould not be observed, but an increase in the sugar contents could be seen.
4) When they were accumulated in stem, the starch grains appeared at first in theouter side of cortex and then gradually entered into inside of the stern. Whilest, whenthey were lost, their decrease were observed at the bark at first and then at the inside ofcortex. In the wood part, their increase and decrease occured at the same time throughthe tissue.
5) It was found that in stems and branches of the Quercus trees a special tissue forreserving starch grains were formed between periderm and primary cortex. The tissueswere formed from the middle of September till the beginning of October. In autumn a lotof starch grains accumulated in the tissues but in winter they disappeared from them.
