1. Concerning the formation of starch in guard cells, the author studied the increase or decrease of starch under natural conditions, the effects of concentration of hydrogen ions, amylase, plant juice and inorganic compounds on the formation of starch, and the substratum for the formation of strach.
2. Over ten kinks of plants were used as materials.
Gladiolus and
Zea Mays were appropriate to the experiments in the summer season,
Narcissus Tazetta and
Zephyranthes candida in the winter season and
Tradescantia reflexa in all seasons. These plants were very suitable, because they had strong power of synthesizing starch from glucose-1-phosphate.
3. Daily increase or decrease of starch in guard cells under natural conditions is not so remarkable as in tissue cells, though remarkable difference by species was observed. When put in dark room, the starch within tissue cells rapidly disappeared, but that within guard cells, in some plants at least, increased for the first two or four days, thenceforth began to decrease little by little, and finally disappeared.
4. Different from in tissue cells, the starch in guard cells was never formed from carbohydrates, but only from glucose-1-phosphate, its lower limit of concentration for the formation being 0.0005mol.
5. The strach-forming activity in guard cells was stronger in the existence of weak acids, and the action of phosphorylase was recognized between the pH of 4.1-7.3 coinciding with the pH value at which the reserve starch of radishes was formed.
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