THE PSEUHO-ANTAGONISM OF SODIUM AND CALCIUM 
IN DILUTE SOLUTIONS ‘ 
By H. S. Reed, Professor of Plant Physiology, and A. R. C. Haas, Assistant Professor 
of Plant Physiology, College of Agriculture, University of California 
The effects of calcium and of sodium ions upon living organisms are 
so diverse that many physiologists have advanced the idea that these 
ions antagonize each other at the surface of the cell. Osterhout (6) * has 
suggested that antagonism depends upon the production of a union of 
NaCl and CaClj with some constituent of the protoplasm, and that the 
surface may become saturated with the antagonizing salts. Below the 
saturation point it is claimed that the relative proportions of the salts 
will be of less importance than their total concentration. In other 
words, it is considered that no distinctly favorable ratios exist in solu¬ 
tions of low concentration. 
An attempt to demonstrate antagonism between Na and Ca in dilute 
solutions was made by Breazeale and Reed (7). The results of their 
inquiry showed an apparent antagonism existing in solutions containing 
230 parts per million of total solutes. At any rate, wheat plants made 
somewhat better growth in ratios of CaClj and NaCl in which Osterhout 
had found the greatest amount of antagonism than in other ratios. 
The large amounts of calcium found by Kelley and Cummins (5) in 
citrus plants, suggested the suitability of these plants as material for the 
further study of this problem. In the first experiment rough-lemon 
(Citrus limonia) seedlings were grown in solutions of NaCl and CaClj 
containing the following mixtures (the pure solutions each being 0.004M) 
looNaro Ca; o Na: 100 Ca. 
The distilled water used in experiments i and 2 was found to be cal¬ 
cium free as determined by evaporating 500 cc. of the water to a small 
volume and testing for calcium. 
Titer glass jars, each containing six seedlings, were filled with culture 
solution on April 23. The seedlings were supported in paraffined-cork 
stoppers in sudi a way as to exclude foreign matter from the culture jars. 
The solutions were renewed on May 5, 13, 24, and June i. The cultures 
were grown out of doors under half shade (in a lath room about 3 feet 
high with sides of cheesecloth) in a south exposure. On June 7 the ex¬ 
periment was concluded. The seedlings were momentarily dipped into 
and well rinsed in distilled water in order to remove adhering solution 
and also to remove dust from the leaves. In preliminary experiments it 
had been found that 0.033 dxist had accumulated on 39 rough- 
lemon seedlings weighing 14.928 gm. green weight, 2.950 gm. dry weight, 
and 0.233 gm. ash. 
The seedlings were freed from adhering moisture by means of filter 
paper, and the green weight was obtained. The seedlings were dried to 
constant weight at 70° C. and were then ignited in a porcelain dish at low 
heat. The salts in the ash were extracted with hot water and the residue 
^ Accepted for publication Sept. 2, 1922. Paper No. 97, University of California, Graduate School of 
Tropical Agriculture, and Citrus Experiment Station, Riverside, Calif. 
* Reference is made by number (italic) to “Literature cited," p. 757. 
Journal of Agricultural Research, 
Washington, D. C. 
aek 
(753) 
Vo 1 .XXIV,No .9 
June 2, 1923 
Key No. Calif .-34 
