shihd Trelease: Salt Requirements of Wheat Plants 529 
Among the generally unessential elements that have been 
considered by investigators, chlorine is one of the commonest, 
and it has attracted considerable attention among agriculturists 
also. This element is frequently added to the soil as potassium 
chloride in fertilizer practice, and it has even been maintained 
that addition of sodium chloride to the soil results in an in- 
creased yield of certain crops. The present study deals with 
the influence of chlorine upon the growth of plants in a nutrient 
solution that also contains the seven essential elements. 
Chlorine is not required in large amounts, since plants are 
able to grow and mature normally without appreciable amounts 
of this element. Birner and Lucanus (1886) concluded that 
chlorine was not essential; Knop,® after growing many kinds 
of plants, including buckwheat, also concluded that chlorine was 
unnecessary for normal development. Wagner’ obtained ap- 
parently completely developed maize plants when no chlorine 
was in the culture solution. Recently Prianishnikov,* employ- 
ing both the water-culture and the sand-culture methods, was 
unable to establish the necessity of this element. Shulov ® con- 
cluded after several years of experimentation that chlorine is 
not necessary for the normal development of buckwheat plants. 
Other investigators have found that many plants make very 
good growth without a chloride in the culture solution, and in 
no case has the necessity for the element chlorine been demon- 
strated. Crone,” using a nutrient solution without chlorine, 
found that rape, barley, grape, and maize made excellent growth. 
Shive found that young wheat plants made better growth in 
a three-salt nutrient solution, containing the same salts as em- 
ployed by Birner and Lucanus, than in any chloride-containing 
solution that he tested. Buckwheat also matured in Shive’s 
*Knop, W., Quantitative Untersuchungen iiber den Ernahrungsprocess 
der Pflanze, Landw. Versuchsst. 7 (1865) 93-107. Knop, W., and Dworzak, 
Ber. d. Sachs. Ges. d. Wiss. (1875) 61. 
"Wagner, P., Wassercultur-Versuche mit Mais. III. Vegetations-Versuche 
mit chlorfreier Lésung, Landw. Versuchsst. 13 (1871) 218-222. 
* Prianishnikov, D. N., Results of vegetation experiments in the years 
1901-1903, Abstract in Exp. Sta. Rec. 18 (1906-1907) 820 and 321. 
*Shulov, L. S., Various smaller experiments with fertilizers and soils, 
Abstract in Exp. Sta. Rec. 22 (1910) 228. 
* Crone, G., Ergebnisse von Untersuchungen iiber die Wirkung der Phos- 
Phorsiiure auf die héhere Pflanzen und eine neue Nahrlésung, Sitzungs- 
ber. Niederrhein. Gesell. Natur- und Heilkunde, Bonn (1902) 167-173. 
" Shive, J. W., A three-salt nutrient solution for plants, Am. Journ. Bot. 
2 (1915) 157-160. A study of physiological balance in nutrient media, 
Physiol. Res. 1 (1916) 327-397. 
