2G2 HIDEO KOUlTiO. 



Eefore the iiTPxliation, lie steeped the gi-aius iu spit water to select them, .lucl 

 then steeped them iu watei' for 168 hours (7 dpys). He placed them flat in 

 a poroelaiu dish after leaving them 4 hoivcs out of the water, and irradiated 

 ■«■ith the al30Te doses. Then they were again steeped in water 2 houre after 

 irradiation and sowed iu a paddy soil, one grain for one stock, 48 hom-s after 

 irradiation. His results were: an acceleratiou of germination was not obseiTed, 

 the growth of the irradiated plants was at first inferior ta the controls, but 

 later the gi'owth of 3 H-plants became the Ijest, and the uumber of tillers was 

 larger than in the others. The 7H- noid lOH-plauts were damaged by insects 

 and fungous disease, and the crop was decreased by these obstructions. The 

 3 H-plants showed 40% increase in the amount of crop. According to 

 the results of the cropping of a liuüted aiea (one "tsubo"), the 3H- and 

 5 H-plants showed 8.3%" and 2.9^^ increase of crop, and the 7 H- and 10 H- 

 plauts 2.4% and 5.4% decrease of crop (this might be caused partly liecause 

 of the damage by insects and disease), »'. e., the 3 H- and 5 H-plants gi\,\e 

 better results than the controls. 



Nakamtjea (1918) published the results of culture-experiments of Orijza 

 sativa (" Sinriki "), of which gi-ains were exposed to X-rays for 5, 10 and 15 

 minutes after steeping in salt water and then cultivated in a ■pi\ßfW soil. He 

 reported that the plants gi'own fi-om seeds with 5 minutes' ex^xjsure showed 

 an increase in the amount of crop. 



The TQ'iter's results (1919) of germiuation-exi^eriments with Oryza sativa 

 (" Sekiyama ")' showed an acceleratiou of germination, and tliat of seeds 

 iiTadiated in air-dried condition %\as more manifest tlian that of iiTadiated seeds 

 after 12 hours steeping. For air-di'ied grains with a water content of ca. 8 %, 

 5 H-10 H was the optimum dose for acceleration. 



From the writer's ex^Deriments (1922) of cultivation of air-di'ied and 

 steeped irradiated plants of Orym satina (" Sekiyama ") in Wagner's pjts and 

 on a paddy soil m 1919 and 1920, it will be seen that the amount of 

 crop in Oryza sativa is not at all iucreas«! l)y the irratliation of X-raA's. The 

 only change produced by irradiation was precocious growth ; young i^lants 

 reached the stage at which they can be transplanted earlier than the control. 



The writer (1922) made a cytological investigp.tion on the root-tii» of 

 1. "Sekiyama" is oue of the pure lines of nn aquatic race of Orijza satifa. 



