STOMATAL MOVEMENT. 



41 



Table 16. Relative transpiration and stomatal openings. 



Date, March 29, 1911. 



Experiment XIV. 



EXPEKIMENT XV. 



Leaves and tangential surface sections of young twigs from tree A were 

 taken simultaneously with leaves from plant No. 1, subjected to the picric 

 acid treatment, and stomatal measurements were made. As a control, 

 stomatal measurements were also made on No. 1 by Lloyd's method, 

 through the 1 o'clock reading. The potted plant was placed in the open, 

 about 50 feet distant from the tree. It will be seen that the agreement of 

 the alcohol method with the picric acid method here is not as good as in the 

 test experiments; however, the lack of agreement is one of actual size only, 

 for the two curves have practically the same shape. The guard cells of the 

 stomata of the tree were always smaller than those of the potted plant. The 

 stomata of the twigs very evidently are not movable to any extent. A few 

 days after this experiment measurements of the stomata of twigs were tried 

 and no evidence of any motion of the stomata was gained from some 20 trials. 



Table 17. Stomatal measurements from leaves and twigs of an adult tree and from leaves 

 of a potted plant. Experiment XV. Date, August 11, 1911. 



'All the rest shut. 



2A11 shut. 



^Average of 6: all the rest shut. 



11 



10 



Fig. 21. Stoniatal measurements from leaves of potted plant and from adult tree by 

 the picric-acid method, with absolute-alcohol method check on potted plant. Exp. XV. 



