i9i6] SHULL— SOILS 



29 



My thanks are due to Professor L. E. Call, of the Kansas State 

 Agricultural College, Manhattan, for sending me the subsoil of the 

 Oswego silt loam used in these experiments, and to Dr. Lyman J. 

 Briggs and his assistants in the biophysical laboratory of the 

 Bureau of Plant Industry for making determinations of the moisture 

 equivalent of the local soils, hygroscopic determinations of the seeds 

 in the vacuum driers, and for the various soil types which were so 

 kindly sent to me. I desire also to express my appreciation of the 

 generous way in which the Hull Botanical Laboratory has provided 

 all needed facilities for the work, and especially my indebtedness 

 and gratitude to Dr. William Crocker for much helpful advice 

 and encouragement received during the progress of the work. 



University op Kansas 

 Lawrence, Kan. 



LITERATURE CITED 



1. Alway, F. J., Studies on the relation of the nonavailable water of the soil 

 to the hygroscopic coefficient. Neb. Agric. Exp. Sta. Research Bull. no. 3. 

 5-122. 1913. 



2. Bancroft, Wilder D., The action of water vapor on gelatine. Jour. Phys. 

 Chem. 16:395-406. 1912. 



3. Bogdanoff, S., Uber das Verhalten der keimenden Samen zum Wasser im 

 allgemeinen, und speziell zur Bodenfeuchtigkeit. Landw. Versuchs-Stat. 

 42:311-366. 1893. 



4. Brown, A. J., On the existence of a semipermeable membrane enclosing 

 the seeds of some of the Gramineae. Ann. Botany 21:79-87. 1907. 



5. Brown, P. E., and Smith, R. E., Bacterial activities of frozen soils. Iowa 

 Agric. Exp. Sta. Research Bull. no. 4. 1912. 



6. Briggs, L. J., and McLane, J. W., The moisture equivalents of soils. 

 Bur. of Soils Bull. no. 45. 1907. 



7. Briggs, L. J., and Shantz, H. L., The wilting coefficient and its indirect 

 determination. Bot. Gaz. 53:20-37. 1912. 



8 - , The wilting coefficient for different plants and its indirect deter- 

 mination. Bur. Plant Industry Bull. no. 230. 1912. 



9. Caldwell, J. S., The relation of environmental conditions to the phe- 

 nomenon of permanent wilting in plants. Physiol. Res. 1: 1-56. 1913. 



10. Cameron, Frank K., The soil solution. 191 1. 



11. Carter, William T., Jr., and Smith, Howard C, Soil survey of Riley 

 County, Kansas. Sth report, Field Operations of the Bureau of Soils, 

 pp. 911-941. 1906. 



