1913-14.] BOTANICAL SOCIETY OF EDINBURGH 



293 



while the growing region of the root is less than in any of 

 the others, including the Dark. 



Table II. 



Table II. shows the average increase in mm. in the 

 growth of roots and shoots and the increase in the length 

 of the growing region for the same periods under the four 

 sets of conditions, beginning with organs of approximately 

 equal length. 



This, in the main, bears out the conclusion, based on 

 Table I., of mean growing regions in roots and shoots, and 

 also gives a comparison between the actual increase of 

 growth in length of the organ and the increase of the 

 growing region. 



It shows that the growth and the length of the growing- 

 regions vary in the same manner, except in the case of 

 etiolated plants. 



The actual growth in length of the etiolated shoot is 

 greater than in any of the others, while the growing region 

 is smaller ; while in the root the growth in length is more 

 than in anj^ of the others, but the growing region is less 

 than in all the others except IV. (Light). 



In the Light shoot the increase of growth is least of 

 all, and the growing region smaller than Normal or Inter- 

 mittent, but bigger than in the Dark. 



In the root in the Light both are smaller than any of 

 the others, probably due to retardatory effect of light on 

 the root. 



The graphs appended (Plates X VIII., XIX., figs. I., II., III., 

 and IV.) are plotted from tables giving the lengths of the 

 organs — root and shoot — from day to day and the figures 

 obtained for the increase of growth every twenty-four 



