and sugar content, but when the dosage was 

 increased, they observed a decrease in the one 

 or the other. The amount of substance used 

 for respiration did not increase by comparison 

 with the controls, but neither did it diminish 

 with large doses of radiation. These results 

 indicate that under the conditions of this experi- 

 ment irradiated seeds cannot convert their 

 reserve starches into sugars as easily as nor- 

 mal seeds, nor can they use their sugar for 

 growth as rapidly as the controls. 



The effect of radiation on seeds of citrus 

 fruit was investigated by Haskins and Moore in 

 1935. They observed a curious phenomenon of 

 premature flowering of two grapefruit plants 

 grown from seeds that had been exposed to doses 

 of 300 and 1300 r. One of the plants was an 

 albino and, consequently, was nonviable; the 

 other developed more or less normally, despite 

 its dwarf size, and after a few months exhibited 

 a second blossoming. 



The experiments of Long and Kersten in 

 1936 were conducted with soya under field con- 

 ditions. The irradiated and control seeds pro- 

 duced a total of 12, 751 plants. When the first 

 beans were formed, the plants were cut off at 

 ground level and weighed. The weight of the 

 green part of the plant was greater in the 

 irradiated plants. Since the experiment was 

 conducted with large numbers of plants which 

 had been allowed to grow under normal condi- 

 tions, and since the average increase in weight 

 of the irradiated plants, as compared with the 

 controls, exceeded the standard deviations three 

 times over, the authors came to the conclusion 

 that this indicates a true stimulating action of 

 the radiation, although not an absolute proof 

 of it. 



In 1936 Frolov used three plants for his 

 investigations, namely soya, wheat, and flax, 

 which had been used for radiation experiments 

 by many other authors. Irradiation of wheat 

 grains not only accelerated development, but 

 resulted in a 60% increase in yield as compared 

 with the controls. Experiments in 1936 gave 

 somewhat poorer results. X rays have a stimu- 

 lating effect on flax only in the first stages of 

 development; after that a marked depression 

 sets in. Irradiation of soya seeds produced 

 negative results, in contrast to the experiments 

 of Long and Kersten. 



Tushnyakova and Vasilevskii* (1934) set up 

 experiments with sedge ( Cyperus esculentus ), 

 soya, blue lupine, tomatoes, and melons. The 

 sedge was treated with X rays for the purpose 

 of shortening its growing season and causing it 

 to multiply vegetatively. The tubers were 

 irradiated in dry and soaked conditions for 5-, 

 10-, 15-, and 20-minute periods. At first the 

 irradiated tubers lagged behind in their develop- 

 ment, but eventually those which had received 

 15 -minute irradiations moved ahead. Two 



months after exposure the difference between 

 the controls and the irradiated plants was 

 striking. The authors pointed out the differ- 

 ences produced by irradiation which were due 

 to condition of the materials and circumstances 

 of the experiment. In 1933*, 1934*, and 1935* 

 experiments were conducted in the field, and 

 although there was no difference in the time of 

 development, the plants which had been irradi- 

 ated for 35 minutes stood out sharply because of 

 their height and vigor of development. They 

 had a high yield and a shorter growing season. 



In experiments with soya a shortening of the 

 maturation period, in comparison with controls, 

 was observed. The same thing was observed 

 with blue lupine where the irradiated plants 

 ripened 12 days earlier than the controls. The 

 experiment with melons was not concluded, but 

 it showed that the plants which had received 

 200 r ripened earlier than the controls. Irradi- 

 ated Mexican tomatoes ripened more rapidly 

 than the controls and the number of fruits and 

 their weight were greater. 



The experiments of these authors should be 

 considered preliminary, despite the fact that 

 the experiments with sedge were repeated over 

 a period of several years. The small number 

 of samples used in these experiments and the 

 lack of concentration of the data, i. e. , the data 

 were scattered too widely, prevent us from 

 treating these experiments as completely 

 conclusive. 



Tsuryupa* (1935) irradiated seeds of hard 

 wheat Triticum durum variety melanopus , and 

 also those of oats and cotton. After irradiation 

 the seeds were planted in growing dishes and 

 their development was minutely observed. The 

 discrepancy between the development of the 

 vegetative part of the plants and their yield in 

 Tsuryupa' s experiments indicates how different 

 X rays can be in their effect on different plants. 

 In experiments with wheat it was observed that 

 X rays have a greater effect on the develop- 

 ment of the reproductive than on the vegetative 

 organs. On the other hand, when oats were 

 used, the effect was just the opposite. Although 

 X rays do not increase the germination of wheat 

 seeds, they greatly increase their sprouting 

 power. Positive effects in yield were obtained 

 in some cases, exceeding the controls by 60%. 

 In addition, the growing season was shortened 

 so that the irradiated plants ripened 10 days 

 earlier. In the case of flax the author observed 

 the activation of the initial stages of develop- 

 ment, which was followed by depression, while 

 irradiation of soya seeds caused development 

 to be retarded from the beginning. 



A series of experiments was performed by 

 Johnson (1926, 1928, two in 1931, 1933 and two 

 [three] in 1936). In fact, her investigations are 

 being carried on right up to the present [1946]. 

 The wide variety of objects, the thoroughness 



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