224 Salt Proportions [422 



chlorine into the solution. Furthermore, the best 4-salt solu- 

 tion with chlorine contains the three essential salts in nearly 

 the same proportions as those in which they occur in Shive's 

 best 3-salt solution, which has the following composition: 

 0.0180M KH 2 P0 4 , 0.0052M Ca(N0 3 ) 2 , and 0.0150M MgS0 4 . 

 The main difference in this respect lies in the Mg/Ca quoti- 

 ent; in Shive's best solution this quotient has the value 2.88, 

 and in the best 4-salt solution with chlorine it has the value 

 1.72. Both are characterized by relatively high proportions of 

 KH 2 P0 4 , and low proportions of Ca(N0 3 ) 2 , which is rather 

 surprising, since many nutrient solutions heretofore proposed 

 have a relatively high concentration of Ca(N0 3 ) 2 . In gen- 

 eral, the occurrence of the morphological leaf modifications 

 tions recognized as magnesium injury in such series as these 

 (Tottingham, Shive) was not altered by the presence of the 

 chlorine ion in the solution. 



A marked improvement over Detmer's salt proportions was 

 obtained in the present study. The best solution gave an in- 

 crease in dry weight of tops of 27 per cent, and 20 per cent., 

 respectively, over the yields obtained in two solutions of the 

 present series closely resembling Detmer's in salt proportions. 

 An even more marked improvement over the growth obtained 

 with Detmer's exact proportions is reported by Shive, for his 

 best 3-salt solution, which, as has been mentioned, gave prac- 

 tically the same yield as did the best 4-salt solution used in 

 this study. 



While it seems impossible to obtain higher top yields of these 

 plants in the 4-salt solution containing chlorine, than in the 

 3-salt solution without this element, it should nevertheless be 

 remarked that the presence of chlorine may diminish to some 

 extent the retarding effect produced by the three salts of the 

 essential elements when these are not in the best proportions. 

 Thus, if we start with an unbalanced. 3-salt solution, a proper 

 addition of chlorine may sometimes accelerate the growth of 

 the plants. The addition of a non-essential element may im- 

 prove the physiological properties of a solution containing the 

 essential elements in improper proportions. 



