324 MACDOUGAL AND SPOEHR— GROWTH AND IMBIBITION. 



Growth of "Turkey Red" Wheat (Triticum). — Concluded. 



April I 



9:30 A.M. (15.5 hours — growth .1 mm.; stopped). 

 Total length 470 mm. 



Retardation of growth of Zca and Triticum occurs at more than 

 one place in the temperature scale and at different times of the day, 

 as may be seen from the inspection of the bold-faced figures on the 

 preceding pages. An uneven rate of elongation was particularly 

 noticeable in Triticum, aUhough displayed by Zca as well. It was 

 thought that the irregularity might be due to a sagging of the leaf 

 blade which would cause its tip to move with a varying rate across 

 the field. Similar leaves attached to the bearing arm of an auxo- 

 graph under a stretching tension traced an undulating line indicative 

 of similar irregularities (Fig. 6). Cessation of growth, especially 

 in some of the instances in Zca, may be reasonably attributed to a 

 direct temperature effect, especially in the cases in which the ther- 

 mometer stood at 30° C. to 35° C. for extended periods. In the 



