Abstract: In order to study the boll shedding of the unfertilized ovaries, a series of field experiments were made and the results are summarized briefly as follows: Heavy dropping of young bolls occurred 4–5 days after raining, because the processes of pollination were prevented by rain after the openning of flowers. The destructive effect of rain continued from morning till 4 p. m. of the rainy day. In addition, it was found that the boll shedding induced by the spraying of liquid insecticide in the forenoon was more serious as compared with that sprayed in the afternoon and the untreated control. Thus, to keep the destructive effect of insecticide and fungicide on the young boll at minimum, it is suggested that their spraying should be practiced after 4 p. m. A further experiment was performed to study whether the unfertilized ovary could develop into seedless boll. The style of flower was removed to prevent pollination. In order to get sufficient food materials for the development of unfertilized ovaries the fruit branch with one flower and two leaves was ringed at the lower end near the main stalk. At the end of the experiment it was found that none of the treated flowers had dropped and the unfertilized ovaries had developed into parthenocarpic fruits with short fibres. The results obtained indicate that if the organic food materials are sufficient, all the bolls may develop without pollination and fertilization. It is, therefore, suggested that organic food plays a fundamental role in the development of fruit. The current theory that only the growth hormone is responsible for the formation of parthenocarpic fruit becomes questionable. It seems that in the processes of fruit development, the stimulative substances or auxins function as a supplementary factor. On the basis of this idea, the general consideration for the control of boll shedding in cotton plant is discussed.