170 AMERICAN JOURNAL OF BOTANY [Vol. 8 
5. Harvey, R. B. Hardening process in plants and developments from frost injury. 
Jour. Agr. Res. 15: 83-1 11. 191 8. 
6. Iljin, W. S. Die Regulierung der Spaltoffnungen mit der Veranderung des osmotichen 
Druckes. Beih. Bot. Centralbl. 32: 15-36. 1914. 
7. Landolt, H., Bornstein, R., and Roth, W. Physikalisch-chemische Tabellen. 1912. 
8. Livingston, B. E. Role of diffusion and osmotic pressure in plants. 1903. 
9. Osterhout, W. J. V. The permeability of living cells to salts in pure and balanced 
solutions. Science n. ser. 34: 187-189. 191 1. 
10. Osterhout, W. J. V. A comparative study of permeability in plants. Jour. Gen. 
Physiol, i: 299-304. 1919. 
11. Renner, O. Ueber die Berechnung des osmotischen Druckes. Biol. Centralbl. 32: 
486-504. 19 1 2. 
12. True, R. H., and Bartlett, H. H. The exchange of ions between the roots of Lupinus 
albus and culture solutions containing one nutrient salt. Amer. Jour. Bot. 2: 
256-278. 1915. 
