On the Effect of Rontgen Rays upon 

 the Growth of Oryza sativa>\ 



By 



Hideo Komuro. 



Yamada 2) (1917) observed the increase of amount of crop in 

 " Takenari," an aquatic race of Oryza sativa, by weak irradiation 

 (3H and 5H), and Nakamura 3 ) (1918) obtained the same result in 

 exposing the seeds of an aquatic race, " Sinriki," to Rontgen rays 

 for five minutes. 



In 1919 and 1920, the writer made the same experiments on 

 " Sekiyama " (Hill) 4 ' which received from Mr. I. Nagai of the Rikuu 

 Experiment Station of the Department of Agriculture and Commerce. 



Irradiation was made by Dr. Koiti Fujinami at the Rontgen 

 Laboratory of the Juntendo Hospital in Tokyo. The writer wishes 

 to express his hearty thanks for his kindly help. The Rontgen ray 

 bulb used was Giba's water-cool tube with a hardness of 4.5—6°. 

 The current passing through it was 2-4, 5-8, and 10 milliamperes, 

 and the doses given were 5H, 10H and 15H for steeped and air- 

 dried seeds, and 3H, 5H and 7H for steeped seeds. 



The writer's experiments were carried on both in Wagner's 

 pots and at the watered fields of Mr. Kazutika Okura, which is 

 situated at Kamata near Tokyo. 



A. Results obtained from Pot Culture. 



1. Steeped Seeds 5) .. 

 In the plants, from the seeds irradiated when their water con- 



1) It is the writer's pleasant duty to acknowledge his indebtedness to .Prof. 

 Naohide Yatsu for his kindness in looking over the manuscript. 



2) Yamada, M : — On the effect of Rontgen rajs upon the development of the 

 seeds of Oryva sativa. " Irigaku Ryoho Zassi" (Journal of Physical Therapy) No. 6, 

 1917 (in Japanese). 



3) Nakamuba, S : — On the comparative <. xperirnents on the effect of X-rays. " K6- 

 no-Kwai Kwaiho " (Proceedings of Kon6-Kwai) No. Ill, April, 1918 (in Japanese). 



4) "Sekiyama" is one of the pure lines of an aquatic races of Oryza sativa. 



5) The seeds were divided into four lots, one of which being used as control. 

 It need hardly be mentioned that the control seeds were subjected to exactly same 

 conditions, excepting irradiation, as other lots, both in the 1919 and 1920-experiments. 



