A'l'KiNS — Bibliography. 433 



Nathansohn, a., 1907. — Ber. u. d. Verhandl. d. k. Sachs. Gesellsch. d. 



Wissenscb. zu Leipzig-niath-nat. Klasse. Bd. 59. Cited. 

 Nef, J. U... 1911. — Dissoziationsvorgange in der Zuckergnippe. Liebig's 



Ami., 403, 204-.383. 

 Oden, S., 1921. — The application of physico-chemico methods to the study 



of humns. Tians. Faraday Soc. Meeting, May 31st, on Soil. 

 OSTERHOUT, W. J. v., and Haas, A. E. C, 1918.— On the dynamics of 



photosynthesis. J. Gen. Physiol., 1, 1-16. 

 Praegee, E. L., 1921.— The genus Sedum. J. E. Hort. Soc, 46, 1-308. 

 Eoaf, H. E., 1920.— Graphic conversion of Sorensen's pH (- logH) into 



concentrations of hydrogen ions. J. Physiol., 54, p. xvii. 

 Eussell, E. J., 1912. — Soil conditions and plant growth. London. 

 Salisbury, E. J., 1920. — The significance of the calcicolous habit. J. EcoL, 



8, 202. 

 Schmidt, C. L^ A., and Hoagland, D. E., 1919. — Table of P„ U+ and Oil- 

 values corresponding to electromotive forces determined in hydrogen 



electrode measurements, with a bibliography. Univ. of California, 



Publ. in Physiology, 5, No. 4, 23-69. 

 Sharp, L. T., and Hoagland, D. E., 1919.— Notes on recent work coneernino- 



acid soils. Soil Sci., 7, 197. 

 Shedd, 0. M., 1919. — Effect of oxidation of sulfur in soil on the solubility 



of rock-phosphate and on nitrification. J. Agr. Ees., 18, 329. 

 Skeats, E. M., 1902.— Univ. Texas Mineral Survey. Bull. No. 2. Cited. 

 Skene, M., 1915. — The acidity of Sphagnum and its relation to chalk and 



mineral salts. Ann. Bot., 29, 65-87. 

 SwANSON, C. 0., Latshaw, W. L., and Tague, E. L., 1921.— Eelation of the 



calcium content of some Kansas soils to the soil reaction as deter- 

 mined by electrometric titration. J. Agr. Ees., 20, 855. 

 Tottingham, W. E., and Hart, E. B., 1921. — Sulfur and sulfur composts in 



relation to plant nutrition. Soil Sci., 11, 49. 

 Tukpin, H. W., 1920. — The carbon dioxide of the soil air. Cornell Univ. 



Agr. Expt. Sta. Mem. 32. 

 UsSHER, "W. A. E., 1907. — The geology of the country around Plymouth and 



Liskeard. Mem. Geol. Survey. 

 Van Alstine, E., 1920. — The determination of hydrogen ion concentration 



by the colorimetric method. Soil Sci., 10, 467. 

 Walker, J., and Kay, S. A., 1912. — The acidity and alkalinity of natural 



waters. J. Soc. Chem. Ind., 31, 1013. 



SCIENT. PROC. E.D.S., VOL. XVI., NO. XXXII. 3 b 



