peters: moisture requirements of seeds. ' 37 



conclusions. 



1. Seeds can germinate when supplied with amounts of 

 water which are below the wilting coefficient for the particu- 

 lar soil used. 



2. A uniform water content remaining in the soil when per- 

 manent wilting occurs in the plants growing in it, regardless 

 of species, does not hold true for seeds germinating in such a 

 soil even when the amount supplied could have been used in 

 germination. 



3. While the amount of water used by seeds for germina- 

 tion may be more or less constant when moisture is abundant, 

 they may germinate with far smaller quantities when the sup- 

 ply is scanty. 



4. When the supply of moisture is scanty, the time re- 

 quired for germination is correspondingly lengthened. 



BIBLIOGRAPHY. 



1. Briggs, L. J., AND Shantz, H. L.,The wilting coefficient and its in- 



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



2. Caldwell, J. S., The relation of environmental conditions to the 



phenomenon of permanent wilting in plants. Physiological Re- 

 searches, 1:1-56, 1915. 



3. Clements, F. E., Research Methods in Ecology, p. 30, 1905. 



4. Hedgcock, G. G., The relation of the water content of the soil to 



certain plants, principally mesophytes. Studies in the vegetation 

 of the state, part 2, 1902, pp. 5-79. In Bot. Surv. of Nebraska, 

 vol. 6. 



5. Livingstone, B. E., Incipient drying and temporary and permanent 



wilting of plants, as related to external and internal conditions. 

 In Contributions to Plant Physiology, p. 176. Reprints from The 

 Johns Hopkins University Circular, March, 1917. 



6. Russell, E. J., Soil Conditions and Plant Growth, 1912, p. 104. 



7. Sachs, J., Bericht uber die physiologicale Thatigkeit an der Versu- 



chsstation in Tharandt. Landwirtschaftlichen Versuchs Stationen, 

 1859, vol. 1, p. 235. 



8. Shull, C. a.. Measurement of the surface forces in soils. Bot. Gaz., 



62:7, 1916. 



9. , Measurement of the internal forces of seeds. Trans. 



Kans. Acad. Sci., 27:65-70, 1915. 



10. Widtsoe, , Dry Farming, p. 209. 



Army service interrupted this work and it is not now convenient to 

 resume it. Its imperfections are realized, but it is hoped that it adds 

 something to our knowledge in this field and that it may suggest further 

 investigation. 



