256 HIDEO KOMÜRO. 



He recognized the practicability of X-rays, based on this positive stimulus by 

 weak irradiation, and fouud an acceleration of growth. 



Wettereb (1913) divided seeds of Helianthiw anmm% which had been 

 «teeped in water for 3 days, into five parts, one of which was taken as the con- 

 trol and the rest exposed to the rays of 5 H, 10 H, 20 H, and 40 H. Then they 

 were sown in a rich soil. The control, 5 H- and 10 H-plants sprouted almost 

 at the same time, the 20 H-i^lants came out Liter and crooked. Of the 40 H- 

 seeds noiie germinated.' Compared "with the control, the 5 H-, 10 H- and 

 20H-plant3 showed an inferior growth j)roportional to tlie increase of ths 

 dose. He cropped the seeds fi-om the 20 H- plants as well as the control aup 

 sowed them in soil in the Ijeginning of the nest summer (Friihsommer). From 

 the control seeds, stout plants developed, but from the 20 H-sesds shoi-ter and 

 worse developed plants than tlie control were obtained, yet they were better 

 than the mother pknts, h'orn which the seeds were derived. The second 

 generation of the irradiated plants, which were impeded in their earlier 

 development was worse in growth, but the impediment was less than in the first 

 generation. The seeds cropped from these plants were sown out next year, 

 the resulting plants had the normal form and height, and there was no 

 change. Thus, he concluded that the effects of Röntgen rays do not ap][5ear 

 in the third generation. According to the results of his ex^xsriments, the 

 state of impediment in the same hj'adiated material is proportional to the 

 doses given. 



' Eewin Schwakz (1913) made experiments in order to find: 'wo lag das 

 Optimum jener Strahlenmenge, die wir far die Reizwirkung brauchten ? ' 

 and ' in welchem Stadium der Eutwicklimg der Reiz einsetzen mußte, wenn er 

 in günstiger Weise zur Geltung kommen sollte ', and he said " diiß es mir 

 nur dann gelang, eine Wachstumsl)esGhleuuiguug zu erzielen, wenn ich Siimen 

 vor der Auskeimung oder ganz jimge, eben ausgekeimte Triebe bestrahlte, 

 während es sich ti'otz aller mögUcheu Versuclisanordnungen als uumüglich 

 erwieg, altere, bereits heranwachsende Pflanzen zu beschleunigtem Waclistum an- 

 ziu-egen". Tho writer gives here the results of liis experiments. He irradiatetl 

 di-ied seeds of Vic ia /aha as in the following table, and comiiared the length 



1. The writer presumes that by "nicht nufgeheii " the nulhor mentis that the i>lumule 

 did uot cume out ou the surface of the soil 



