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,PO,, 0.0052M Ca(NO,),, and 0.0150M MgSQ,. 
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,PO,, and low proportions of Ca(NO,),., which is rather 
surprising, since many nutrient solutions heretofore proposed 
have a relatively high concentration of Ca(NO,),. 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. 
