IQ THE BOTANICAL MAGAZINE. CVoi. xxxvi. No. 421. 



tent 1 ) reached 16.85 % by 12 hour steeping in water of 17.2-22.8° 

 C, the number of tillers decreased proportional to the doses given 

 (in 1919-experiments, sparrows ate up seeds entirely, so that the 

 amount of crop could not be determined). The doses were 5H, 10H 

 and 15H. 



In 1920-experiments the results were negative. Seeds were steep- 

 ed in water of 16-19° C. for 12 hours (water content was 19.32 %) 

 and exposed to the rays of 3H, 5H and 7H. The number of tillers 

 and the amount of crop decreased proportional to the doses given. 



In the case of the above two experiments the results were 

 negative. 



2. Air-dried Seeds. 



In two experiments performed in 1919 and 1920 on air-dried 

 seeds, the writer observed no conspicuous difference in the number of 

 tillers and the amount of crop comparing with the controls from the 

 seeds equally treated. The water content of air-dried seeds used 

 were ca. 8 % and 12.45 %. The seeds were divided into four lots 

 (one as the control) and irradiated by 5H, 10H and 15H respectively. 



B. Results obtained from Watered-field Culture. 



The writer 'cultivated the steeped and air-dried seeds, which had 

 come from the batch of the pot culture of 1920, i. e., the plants from 

 the steeped seeds were irradiated by 3H, 5H and 7H and those of the 

 air-dried by 5H, 10H and 15H. 225 plants were used for each lot. 

 Care was taken to minimize the differrence in fertility of the soil 

 used. Fertilizers given were calcium superphosphate, ammonium sul- 

 phate and wood ash. 



No conspicuous difference in the amount of crop was found 

 between the air- dried and the steeped seeds. The only change pro- 

 duced by irradiation was the precocious growth ; young plants reach- 

 ed the stage at which they can be transplanted earlier than the 

 control. They were yellowish green. The results might give an 

 erroneous idea that in both cases a certain dose exerts a positive 

 stimulation. Careful examination, however, will soon reveal that it 

 is not the case, since the loss of the number of tillers due to the 

 damage caused by rats, birds, insects, diseases and storm was not little. 



1) The water content of the seeds used was kindly determined by Mr. Fumi- 



HABU YAMAMURA. 



