UPWARD TRANSPORT OF NITROGEN 



49 



each pair of opposite leaves was taken at the beginning, 

 Aug. 25, 1920, and its mate was harvested at the end of the 

 experiment. It is noticeable that the leaves of ringed and 

 check stems increased in ash and nitrogen contents, but 

 the increases in the check stems were from 3 to 5 times 

 those in the ringed. Another set of stems, started at the 

 same time but harvested after 75 days instead of 39 and 40 

 days, respectively, showed changes very similar to those 

 presented in Table 9. 



Table 9. — Effect of Ringing on the Gains in Nitrogen and Ash 



Content of Leaves of Ligiistrum 



Paired leaves taken one at beginning and the other at end of experiment. 



Each figure is the amount per stem, an average of 12 separate 



determinations 



Area of leaves 



Dry wt., g 



Total nitrogen, mg 



Nitrogen, mg. per sq. dec. 

 Nitrogen, mg. per gm. dry 



wt 



Total ash, mg 



Ash, mg. per sq. dec 



Ash, mg. per g. dry wt. . . 



Check 



Aug. 

 25 



0.956 

 1.130 

 16.43 

 17.07 



14.41 



85.4 



92.0 



77.8 



Oct. 3 

 and 4 



1.104 

 1.376 

 34.51 

 32.36 



24.81 

 139.9 

 127.2 

 101.4 



Av.* 

 gain. 



16.6 



22.9 



115.9 



82. 4 



67.6 

 61.1 

 38.8 

 30.8 



Ringed 



Aug. 

 25 



0.902 

 1.033 

 14.10 

 16.14 



13.90 

 79.8 

 91.9 

 79.8 



Oct. 3 

 and 4 



1.017 

 1 . 696 

 17.38 

 16.88 



10.13 

 95.2 

 95.1 

 57.1 



Av.* 

 gain, 



12.9 



66.2 



22 7 



6.5 



-25.5 



20.7 



3.8 



-27.2 



Differences, 



'i gain in check 



in excess of that 



of ringed 



3. 



-43. 



93. 



75. 



105.3 

 40.4 

 35.0 

 58.0 



* The gain for each stem was determined separately and then averaged. 



Other experiments with comparable results were carried 

 out with peaches, apple, and lilac. Some of the data are 

 presented in the earlier paper (1923). Additional data are 

 presented by MacDaniels and Curtis (1930). With the 

 lilac, however, the leaves from the ringed branches showed 

 a slight actual loss. This loss may have been due to 

 leaching by rains. A number of workers (LeClerc and 

 Breazeale, 1908; Mann and Wallace, 1925; and others) 

 have observed a removal of potassium by rains. In a few 

 instances, in which the experiments were started late in 



