63 



In the first iiroup of I.inuni plants studied, the average 

 number of main hrancht-s of the X-ra>-ed plants was exactly 

 twice that of the controls. Representative specimens of the 

 group portra\'ed in the figure exhil)it the two most outstanding 

 features of the treated plants: a greater number of branches 

 sent up from the crown, and increased development of second- 

 ary branches from the central stalk. It is apparent that the 

 main central stalk, in certain [)lants, was replaced by numerous 

 branches of apparently equal size. 



In the second study of scarlet flax, seedlings 15 days old 

 were irradiated for 20 minutes with the following "set-up": 

 91 K.V., 5 ma., distance 30 cm. A careful analysis of the 

 measurements taken at maturity made clear the fact that the 

 decrease in total height of the treated plants was caused by 

 lessened growth of the central stalk up to the point where it 

 divided to produce the terminal branches rather than to reduced 



Growth of Linum grandiflorum (Group II) 



(15-day-old seedlings were treated with 1 dose 



"set-up": 91 K.V., 5 ma., 30 cm., 



No. of plants 



Average height of plants (in cm.) 



Central stalk 



Av. length to point of division into ter- 

 minal branches (in cm.) 

 No. of terminal branches 

 Av. length of terminals per plants 



(in cm.) 

 Percentage of plants bearing laterals on 



central stalk 

 Av. no of lateral branches 

 Av. length of lateral branches (in cm.) 



Average number of branches other than on 

 central stalk 



Av. no. of days before blossoming oc- 

 curred 



Av. no. of fresh blossoms at close of experi- 

 ment (165 days) 



AFTER X-RADIATION 



from machine with 

 20 min.) 



Percentage 



^ontrol 



Irradiated 



treated 

 plants 



15 



15 





39.5 



33.5 



-\S.2- 



28.5 



22.7 



-19.5 



43 



44 



-f2.3 



30.4 



33.6 



-flO.5 



53.3 



86.7 



+62.7 



1.9 



4.0 



-fllO.5 



6.9 



26.1 



+ 278.2 



14.7 



14.5 



-1.4 



124 



126 



+ 1.6 



7.3 



6.9 



-5.5 



* The minus sign indicates that the treated showed less growth than the 

 controls; the plus sign that they exhibited greater growth. 



