210 
AMERICAN JOURNAL OF BOTANY 
[Vol. io 
5. Ferric citrate supplied at the rate of 10 milligrams of iron per liter 
of the nutrient solution employed here is not completely dissolved, but seems 
to provide abundant iron for the growth of the young wheat plant, where 
the nutrient solution is renewed. 
Department of Agricultural Chemistry, 
University of Wisconsin 
BIBLIOGRAPHY 
1. Bureau of Standards, U. S. The colorimetric determination of iron with special refer¬ 
ence to chemical reagents. Bull. 3. 1907. 
2. Clark, W. M. The determination of hydrogen ions. Baltimore, 1920. 
3. Committee on Salt Requirements of Plants, Division of Biology and Agriculture, Na¬ 
tional Research Council. A plan for co-operative research on the salt requirements 
of representative agricultural plants. Edited by B. E. Livingston. 2d. ed., Balti¬ 
more, 1919. 
4. Corsan, G. E., and Bakke, A. L. The use of iron in nutrient solutions for plants. Proc. 
Iowa Acad. Sci. 24: 477-482. 1917. 
5. Duggar, B. M. Hydrogen-ion concentration and the composition of nutrient solutions 
in relation to the growth of seed plants. Ann. Mo. Bot. Gard. 7: 1-49. 1920. 
6. Gile, P. L., and Carrero, J. O. Cause of lime-induced chlorosis and availability of iron 
in the soil. Jour. Agr. Res. 20: 33-61. 1920. 
7. -. Assimilation of iron by rice from certain nutrient solutions. Jopr. Agr. Res. 7: 
503-528. 1916. 
8. Hoagland, D. R. Relation of the concentration and reaction of the nutrient medium to 
the growth and absorption of the plant. Jour. Agr. Res. 18: 73-117. 1919. 
9. Jones, L. H., and Shive, J. W. The influence of iron in the form of ferric phosphate 
and ferrous sulphate upon the growth of wheat in a nutrient solution. Soil Sci. 
11: 93-99- 1921. 
10. -. Effect of ammonium sulphate upon plants in nutrient solutions supplied with 
ferric phosphate and ferrous sulphate as sources of iron. Jour. Agr. Res. 21: 701- 
729. 1921. 
11. Livingston, B. E., and Tottingham, W. E. A new three-salt nutrient solution for plant 
cultures. Amer. Jour. Bot. 5: 337-346. 1918. 
12. McCall, A. G., and Haag, J. R. The relation of the hydrogen-ion concentration of the 
nutrient solution to growth and chlorosis of wheat plants. Soil Sci. 12: 69-77. 1921. 
13. Toole, E. H., and Tottingham, W. E. The influence of certain added solids upon the 
composition and efficiency of Knop’s nutrient solution. Amer. Jour. Bot. 5: 452- 
461. 1918. 
