STUDIES IN THE EFFECT OF RÖNTGEN KAYS, ETC. 283 



Tlio seotb wove iiTadinktl uu April 19, 1919 und sown in tlio cvoninp; of 

 tbit day. The controls sprouted on April 26. Tbo seedlings were photugi-aphed 

 on Aiffil 27 (Fig. 17). The lower row represents those fix>m peeled seeds. 

 From this cxixirimcnt it will U- se<-n that, 



1. No conspicuoiis diflerence was seen in the growth of seetUings 

 irrachated in diflerent doses. 



2. The seedling? fi'om iiradiated seeds whether peeled or not, gi-ew 

 alilce. 



3. The tip of the radicles from irradiated seeds is stunted and harder 

 than that of normal seedlings. 



4. Tiiero is no acceleration of germination in h-radiated seeds. 



By this experiment the writer could verify the common results of several 



foiTner experiments i. e. " the seedlings which do not appear above the soil 



cease to grow at almost the same st:ige, and there is no difference in growth 

 pixjportional to the doses given ". 



Experiment IX. 



In order to see if there is acceleration of germination in air-dried seeds 

 iiTadiated weakly, the following experiment was performed. 



If ah-dried seeds, with a water content of 10A9% were exposed (Juno 

 25, 1919) to rays of 7 H, 10 H and 15 H'. 8 ^ hours after irradiation they 

 were steeped in water for 12 houre, and then sown in a square pot with 

 washed sands, and divided into fom* compartments. 



The writer recognized such a seedling as of perfect germination, the 

 plumule of which protrudes from the seed coat, and examined the seedlings at 

 10.20 A.^r. on June 30. The germination-percentage was as follows : — 

 Controls 60°^ 



7 H 20.6% 



10 H 46.6% 



15 H 25.0% 



That is, there is no acceleration of gennination in the irradiated seeds. 

 As Fig. 18 shows, they are in almost the same state of growth. 



1. It tooK 13.5 minutes to get 15 H. 



