June 2 ,1923 
Pseudo-Antagonism of Sodium and Calcium 
757 
In the study of the antagonism of Na and Ca with citrus seedlings it 
seems impossible to utilize solutions as dilute as those commonly employed 
as nutrients on account of the starvation which results when the cal¬ 
cium is reduced to extremely low concentrations. In other words, the 
assumption that no distinctly favorable ratios exist in solutions of low 
concentration is supported. 
SUMMARY 
Citrus seedlings grown in absence of calcium soon show injury to the 
root system, as evidenced by the gelatinization of the superficial layers 
and the ultimate death of the root. The tops, however, may not show 
the effect for some time after the injury to the roots has become severe. 
If the injury has not progressed too far, the addition of calcium to 
cultures in which the roots are gelatinized induces the production of 
lateral rootlets the lowermost of which definitely delimits the dead from 
the living portion of the root. 
The varieties of citrus here studied are known to possess a marked 
capacity for the absorption of calcium ions. Hence in very dilute solu¬ 
tions the amounts present may be too far below the equilibrium point 
within the plant to avoid a condition of starvation. In such cases we 
are dealing with the phenomenon of starvation rather than that of 
antagonism. These experiments with citrus seedlings have not demon¬ 
strated the existence of antagonism between sodium and calcium when 
the plants are grown in very dilute solutions. 
LITERATURE CITED 
(1) Hansts^n crann^r, B. 
1910-14. Ober das verhadten der kueturpeeanzen zu den bodensaezen. 
i-ni. In Jahrb. Wiss. Bot. [Pringsheim], Bd. 47, p. 289-376, 19 
fig., pi. II; Bd. 53, p. 536-598, 5 fig., pi. 5-7. Literatar-Verzeichnis, 
Bd. 47, p. 375-376; biblio^aphical footnotes, Bd. 53. 
(2) Herbst, C. 
1900. t)BER DAS AUSEINANDERGEHEN VON FURCHUNGS- UND GEWEBEZEEEEN 
IN kaekfreiEm medium. In Arch. Entwicketogsmech. Organis- 
men, Bd. 9, p. 424-463, pi. 18-19. Bibliographical footnotes. 
(3) Hoageand, D. R. 
1920. OPTIMUM nutrient soeutions FOR PEANTS. In Science, n. s., v. 52, p. 
562-564. 
(4) Johnson, H. V. 
1915. THE absorption of IONS BY EiviNG AND DEAD ROOTS. In Amer. Jotir. 
Bot., V. 2, p. 250-254. 
(5) KeeeEy, W. P., and Cummins, A. B. 
1920. composition of normae and motteed citrus eeaves. In Jonr. Agr. 
Research, v. 20, p. 161-191. Literature cited, p. 190-191. 
(6) OSTERHOUT, W. J. V. 
1921. A theory of injury and recovery. II. experiments with mix¬ 
tures. In Jour. Gen. Physiology, v. 3, p. 415-429, 8 fig. 
(7) Reed, Howard S. 
1918. absorption of sodium and caecium by wheat sEEdeings. In Bot. 
Gaz., V. 66, p. 374-380, I fig. 
(8) True, Rodney H. 
1921. THE function of CAECIUM IN THE NUTRITION OF SEEDEINGS. In Jour. 
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