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seem to group this substance with those in which root absorption is 
greatly reduced and to suggest a close parallel between the NaCl 
solutions and distilled water. 
The growth of the roots in the NaCl solutions here tested was 
depressed to or below the point characteristic of distilled water. 
Conclusions 
1. Roots of Lupiniis albus grown in darkness in distilled water 
give up their salts to the water at a varying rate until the death of the 
plants occur through exhaustion of the reserves. 
2. KH2PO4 and KCl solutions act essentially like distilled water 
in the. concentrations studied by us. Solutions of K2SO4 and KNO3 
show a slight absorption phase resulting in a minimal net gain in salts 
to the plant but otherwise differ little from the phosphate and chloride. 
3. Absorption and growth take place in NaCl essentially as in 
KNO3 and K2SO4. 
4. Solutions of Mg(N03)2 and MgS04 support a slight but clearly 
developed absorption phase resulting in a net gain in salts to the plant. 
A net leakage of salts is seen in the more dilute solutions, and toxic 
action in those of greater concentration. 
5. Calcium nitrate and calcium sulphate in all concentrations 
studied are actively absorbed by the roots and apparently enable the 
plants to retain possession of the salts already present. 
Bureau of Plant Industry, 
Washington, D. C. 
