EFFECTS OF RADIUM RAYS ON PLANTS 997 



tion (0.1 to 0.6 millicurie) sealed in glass capillaries which are implanted in 

 the crown gall tissue produce little effect on the surrounding tissues. 

 Longer exposures and larger doses induce necrosis of tissues immediately 

 surrounding the tube extending progressively to a radius of 0.5 to 5 mm. 



The same author (Levine, 46), reported on the influence of filtered 

 and unfiltered radium emanation on microsporogenesis of species of 

 Lilium (L. Harrisii, L. giganteum, L. auratum, and L. superbum). The 

 radium varied in strength from 0.25 to 3.3 millicuries, and the filters 

 were of platinum, silver, and aluminum of 0.5 mm. in thickness. Various 

 abnormalities and injuries that followed the exposure are described and 

 figured. Three pages of bibliography are given. 



The effect of radium rays on "vegetable cancers" was investigated in 

 Italy by Rivera-Attilj (1925). Pichler and Wober (63) found that, w^hile 

 ultra-violet rays and roentgen rays could be used successfully in the 

 treatment of smutted wheat, the rays of radium were ineffective (at least 

 under the conditions of the experiment). 



Beginning in 1922 Emmy Stein published a series of papers, the first 

 one dealing with the effect of the rays on the growing points of shoots 

 and on seeds. Only the beta and gamma rays were employed. Expo- 

 sures of growing points for 20 to 160 min. checked growth temporarily 

 and caused floral abnormalities of several types. Later the plants 

 assumed normal behavior. The material was from the pedigree cultures 

 of Professor Bauer. No mutation resulted. Seeds exposed 1.5 hr. gave 

 rise to aberrant forms ("radium plants"), some of which were regarded 

 as true mutants, since no such forms had previously appeared in Professor 

 Bauer's cultures. The abnormality was in one case repeated in the second 

 generation. When propagated by cuttings, the "radium plants" pre- 

 served their mutant characters, though single branches of 10 reverted to 

 normal except that they were sterile. 



The poisonous effect of selenium on the germination of seeds was 

 studied by Stoklasa (79, 79a), who found that this effect was largely 

 removed when the seeds were germinated and grown in aqueous solutions 

 either naturally radioactive or rendered so artificially by the presence of 

 radium emanation. In other words, the rays from the emanation 

 counteracted the toxicity of the selenium. The seeds used were Hordeum 

 distichum, Triticum vulgare, Secale cereale, Avena sativa, Vicia Faba, and 

 Polygonum fagopyrum, cultivated in the presence of selenite (Na2Se03) 

 or of selenate (Na2Se04) of sodium. The emanation was supplied at the 

 rate of 0.0000056 mg. ( = 14 ME) per plant per day. 



Nadson (58) investigated the effect of radium on yeast fungi in 

 relation to the question of its effect on living substance in general. He 

 found the following organisms possessed sensitivity to the rays in the 

 order named, the first being most sensitive: Endomyces vernalis, Sac- 

 charomyces cerevisiae, Nadsonia fulvescens, Cryptococcus glutinis. Young 



