

(6) 



(7) 



(8) 

 (9) 

 (1C) 

 (11) 

 (12) 

 (15) 

 (14) 

 (15) 

 (15) 



6 

 6 

 e 



G 



G 

 G 



e 



G 



G= 



G 



f (a 

 f (a 

 f (a 

 f (t 

 f (P 

 f (t 

 f ia 

 f (a 

 f (a 



t <P 

 f (a 



t) , when d, m, p, n ara constant. 



n), 



p), 

 n), 

 n), 



p), " 

 t, n)," 



t, p)," 

 n, p), n 

 t, n)," 



d , m , p , t 



d , it , t , r. 



d, m, p, a 



d , n. , a , t 



d , fti, a, n 



d, a, p 



d , m , n 



d, it, t 



d , m, a 



t ,, p , n ) , " d , m 



The investigation reported in the present paper was 

 carried out during the period between October, 1916, and June, 

 1918, in the laboratory of Plant Physiology of the Johns 



Hopkins University. We author wishes to express his thanks 

 to "Dr. H. J. Webber and the University of California, for 

 arrangements which made it poesjhle for him to be absent from 

 the Citrus Experiment Station during the period just named. 

 He also wishes to record his appreciation of the privileges 

 and facilities accorded him by the Johns Hopkins University, 

 including a Johnston Scholarship in that Institution. 

 Finally, he desires to acknowledge his indebtedness to Prcf. 

 B. E. Livingston ard to Dr. H. K. Pulling, of the Laboratory 

 of Plant Physiology of the John3 Hopkins University, for 

 much valued aid and criticism in correction wi th the planning 

 and carrying out of the experimental part of this study and 

 in the interpretation and presentation of the results. 



P. 9 



