fractional doses. Seeds of lentils, rye, beans, 

 white lupine and kidney beans were used. These 

 experiments resulted in the following conclu- 

 sions: under normal conditions (15°C) the 

 germinating of seeds exposed to X rays was 

 sometimes accelerated and sometimes retarded; 

 when the temperature was raised to 35*^ to 40° 

 the results became more exact. The doses of 

 X rays applied under the higher temperature 

 invariably exerted a beneficial influence on the 

 sprouting and development of the seeds. 



Schwarz (1913) used broad beans (Vicia faba) 

 in his investigations. They were subjected to 

 30-, 60-, 90-, and 150-second exposures. The 

 150-second exposure produced the most favor- 

 able results; plants receiving this dose exhibited 

 the tallest and most vigorous development. 

 Irradiations of five minutes greatly retarded 

 the growth of the plant. However, this retarda- 

 tion did not show up immediately; such plants 

 sprouted at the same time as the others, but 

 eventually their growth stopped altogether, 

 although the plants remained green for a long 

 time. Malformation or atypical development of 

 individual organs was not observed. To avoid 

 discrepancies due to the use of unusually vigor- 

 ous specimens, in the second experiment the 

 most vigorous plants were selected as the con- 

 trol, those next in vigor for the weakest dose, 

 etc. Measurement of the plants 3 weeks after 

 irradiation revealed that the stem length of the 

 control plants was 25 centimeters, a 60 -second 

 exposure to X rays produced 40 centimeter 

 stems, a 90-second exposure 42. 5 centimeter 

 stems, and a 100 -second exposure 43. 5 centi- 

 meter stems, and greater dosages 37 centi- 

 meter stems. Thus, the experiments revealed 

 a typical growth curve due to stimulation. 



In the experiments of Miege and Coup6 (1914) 

 a clearly defined stimulating action of X rays 

 appeared in work with Raphanus and Lepidium . 

 The irradiated plants exhibited a more vigorous 

 development in comparison with the controls. 

 This showed up in a 45% increase in the weight 

 of the leaves, and a 59% increase in the total 

 weight of the green part of the plants. 



In the same year Kornicke continued his 

 experiments and produced several papers (1915- 

 1920) in which he pointed out that since his first 

 experiments (1904) many authors had demon- 

 strated the stimulating action of X rays. Thus 

 he once again began experiments with the seeds 

 of Vicia faba, Phaseolus multiflora , Phaseolus 

 vulgaris , Lupinus albus , Sinapis arvensis , 

 Papaver somniferum , Zea mays, Triticum 

 vulgare , A vena savita and BrassicT ! He delib- 

 erately selected plants whose seeds showed 

 morphological and physiological differences. 

 For each experiment 220 to 300 plants were 

 used and various doses of radiation were 

 applied. In summary he gives a brilliant ex- 

 ample of the Arndt-Schultze Law. Turgid seeds 

 behaved in the same manner: those beginning 



to germinate accelerated their development 

 under mild exposure, whereas they showed 

 retardation with strong exposures. Data from 

 experiments with seeds of various species made 

 it possible to establish the differential sensi- 

 tivity of plants to X rays. Broad bean ( Vicia 

 faba) were the most sensitive to X rays. 



Yamada (1917) soaked grains of rice in salt 

 water for 7 days before irradiation with doses 

 of 3, 5, 7, and 10 H; they were soaked again 

 and then planted in soil. He did not observe any 

 acceleration of germination and the size of the 

 irradiated plants was, at first, smaller than 

 the controls. Eventually, however, the plants 

 which had received a dose of 3 H showed the 

 finest development; they had a greater number 

 of stems per bush and their yield exceeded the 

 controls by 40%. Doses of 7 and 10 H lowered 

 the yield by 2. 4% and 5. 4%, which the author 

 ascribed in part to injury of the plants by insects 

 and fungi. 



Nakamura (1918) gave a brief description of 

 his experiments with Oryza sativa ("Sinriki"), 

 in which the seeds were subjected to 5-, 10-, 

 and 15 -minute exposure after a brief soaking 

 in water. He pointed out that plants from seeds 

 irradiated for five minutes showed an increase 

 in yield. 



Komuro (1919) also established that irradi- 

 ated seeds of Oryza sativa ("Sekiyama") show 

 accelerated germination and that seeds irradi- 

 ated in an air-dry state were less affected by 

 X rays than those soaked for 12 hours. Opti- 

 mum doses were 5 to 10 H. 



Komuro also experimented with irradiation 

 of seeds and sprouts of rice from 1917 to 1922, 

 arriving at the following conclusions: 1) X rays 

 exert a harmful effect on seeds in proportion 

 to the water content of the seeds; 2) develop- 

 ment of the seeds of some plants is accelerated, 

 in other plants, retarded; 3) moderate dosages 

 act as positive stimuli on the seeds; and 4) 

 young plants exhibit a differential sensitivity to 

 X rays. 



In 1920, Jiingling irradiated sprouts of Vicia 

 faba and then placed them in special boxes with 

 glass sides. The length of the roots was 

 marked on the walls every 24 hours. The 

 response to X rays was based on the growth in 

 length of the roots and the time of appearance 

 of lateral roots. Various injuries depending on 

 the size of the dose were observed. He con- 

 sidered as a maximum injury the total cessation 

 of growth in length on the fourth day, and the 

 appearance of lateral roots. The dose capable 

 of producing this he called a "full dose" ("Vol- 

 Idosis"). With a smaller dose, slow growth 

 continued for two more days, then the growth 

 rate accelerated and lateral roots began to 

 appear. This was the "medium dose" ("Mittel- 

 dosis"). Reversing the process, he judged 



