On the origin of fiber cells on epidermis of cotton seed, with special reference to the so-called second period.

[摘要] Author previously reported a conclusion that, in representative Asiatic and upland varieties which were cultivated in Eastern Asia, fibers on the cotton seed continued to form from epidermal cells for a period of 12 or 13 days after the date of flowering, and again two periods of protuberance were recognized n the period mentioned above, i. e. the first was from the time of flowering to 2 or 3 days, and the second from 4 or 5 days to 12 or 13 days, after the day of flowering. The object of this study was to investigate more the second period and to discuss the fact in LANG's hypothesis, that the fuzz hairs began to develope only after the lint pattern had been completely established. Materials used in this study were five Asiatic and three upland varieties, and observations were made on a middle longitudinal section by means of the paraffin method. The results were summarized as follows : 1. In regard to the protuberances of epidermal cells in the second period, it was found no remarkable varietal difference among seven Asiatic and upland varieties, the Zairaikurodane variety being a exception (Fig. 1, 2). The appearances of protuberances in this period was found in a period between 4 and 13 days after the day of flowering, with maximum number on the seventh day, and fibers nearest the chalazal end of ovule were the first to protuberate, while these toward the micropylar end arose gradually later. 2. The Zairaikurodane variety (a strain of Asiatic cotton) with fuzz hairs restricted only upon specific area of the micropylar end of mature seed, indicated very different appearances of protuberances as compared with other varieties. In this variety, the number of protuberated cells in this period were very few and these were restricted around the micropylar end. 3. Protuberated cells in the second period were recognized only in fertilized ovules, but these could never be found in un-fertilized ovelus in which fertilization had been prevented by the removal of the anther before flower opening, and even in the case with treatment of growth-hormone spraying on stigma of emasculated flower. This fact in this study was a contrary result, as compared with the author's previous result that the fertilization had no effect on the protuberance of cell in the first period. 4. As number of protuberated cells increased gradually after the fourth day (Fig, 5, 6), a fiber layer was formed after the eleventh day in consequence of adjoining of protuberated cells (Fig. 7), and in this stage it was obviously possible to distinguish the fiber layer of long hairs protuberated in the first period, and that of short hairs in the second period. Considering this result and the appearances of protuberances of Zairaikurodane variety above mentioned, the author could emphasize again his opinion that the lint hairs would develope from hairs formed in the first period, and the fuzz hairs would originate in the second period.

[学科分类] 农业科学（综合）