286 HIDEO KOMCEO. 



impediment of growth will naturally take place, and it is not reasonable to 

 conclude that his results are caused only by the efifect of the rays. He 

 exposed seeds with radicles about to shoot forth as the result of a few 

 days' steeping, to rays of lOX ( = 5H) and 15X( = 7.5H), and observed a 

 conspicuous impediment of growth 9 days after the irradiation, he gives 

 illustrations in wood cuts in his paper of 1915 (Kg. 2). These results are 

 also questionable compared with the above stated results of the ■miter. 



G. ScHWAEZ states that he cultivated dried seeds (trockene Samen) exposed 

 to the rays of 20 H and observed no difference in growth compared to the 

 tmirradiated controls, but in the writer's experiments of air-dried seeds, with 

 a water content of 13. Vö^^", a conspicuous impediment appeared at 80H (the 

 sprouting percentage of SOH-plants was only iiO%, while that of the controls 

 was 100_%), and no 150H-plants appeared above the soil. The amount of 

 crop decreased proportional to the doses used. As the writer explained at the 

 end of the statement to Experiment VJI, it is to be presumed that the seeds 

 used for his experiments must have been air-dried, not absolutely dried ; for 

 this Mter method entirely depiives the seeds of germinating power. It is to 

 be regretted, that he did not show the water content of the seeds. 



Schmidt's experiments were few iu number and seeds used, and one may 

 presume fi'om the ]Dhotogi-aphs iu his paper that he took no particular care as 

 to the method of cultivation (to avoid the special effect of sun'oundings for the 

 plants situated on the edges). So his experiments lack accui'acy. Such an 

 experiment is not good where the seedhngs are exposed to the rays and then 

 planted again into the sou, as transplanting is hannful to Legumiaosa?. 



The writer is rather inclined to beheve that the increase of the amount 

 of crop due to irradiation as described in the paper by Tamada and Nakamura 

 may not be a real one. (Had they taken more care in cultivating the plants, 

 their results might agree with mine.) 



The writer took great pains to get accurate results, hcediug the faults 

 in experimental methods of other investigators. As Vicia faba has no 

 pure line, he could not use it in the present experiments but he used a 

 special race of it and weighed the seeds for averaging their individual 

 deviation, and special care was taken for avoiding the effect of surroundings 

 to the edges. 



