88 Richard H. Boerkcr 



table seeds, namely that the use of large seeds results in a better 

 all round later development and a greater final crop. 



3. The Rocky Mountain varieties of Pinus ponderosa produce 

 smaller seeds, their germination begins earlier, their germination 

 period is shorter, and their germination curves rise much more 

 rapidly than in the case of the Pacific coast varieties of this 

 species. 



4. Except for the size of the seed, the same relations hold for 

 the Rocky Mountain and Pacific coast varieties of Pseudotsuga 

 ta.vifolia. Blumer noted the slow germination of Pinus pon- 

 derosa and Pseudotsuga ta.vifolia from the coast and he also 

 noted the great difference in size of the seed of Pinus ponderosa. 

 These observations are corroborated. 



BIBLIOGRAPHY 



1. Clements, F. E. Research Methods in Ecology, Lincoln, 1905. 



2. Zon, R., and Graves, H. S. Light in Relation to Tree Growth. U. S. 



Dept. of Agriculture, Forest Service, Bui. 92, 191 1. 



3. Hasselbring, H. The Effect of Shading on the Transpiration and 



Assimilation of the Tobacco Plant in Cuba. Bot. Gaz., 57, 1914. 



4. Stewart, J. B. Effects of Shading on Soil Conditions. U. S. Dept. 



Agric, Bureau of Soils, Bui. 39, 1907. 



5. Haak, J. Die Priifung des Kiefersamens. Zeitschrift fur Forst- und 



Jagd-wesen, April, May, 1912. 



6. Pittauer, E. Uber den Einfluss verschiedner Belichtung und Extremen 



Temperaturen auf den Verlauf der Keimung forstlichen Saatgutes. 

 Centralblatt fur das gesammte Forstwesen, April, May, 1912. 



7. Graves, H. S. The Place of Forestry among Natural Sciences. Sci- 



ence, N. S., XLI. : 117, 1915. 



8. Tolsky, A. P. Work of the Forest Experiment Stations of Russia. 



Review in Forestry Quarterly, III, 1905. 



9. Burns, G. P. Studies in Tolerance of New England Forest Trees. 



Vt. Agric. Exp. Sta. Bui. 178, 1914. 



10. Haberlandt, G. Physiological Plant Anatomy. English edition trans- 



lated from fourth German edition, 1914. 



11. Coulter, J. M., and Barnes, C. R., and Cowles, H. C. A Textbook of 



Botany, 1911. 



12. Clements, F. E. Plant Physiology and Ecology. New York, 1907. 



13. Timiriazeff, T. A. The Life of the Plant, 1912. 



14. Shull, C. A. The Oxygen Minimum and the Germination of Xan- 



thium Seeds. Bot. Gaz., 52, 191 1. 



15. Shull, C. A. Semipermeability of Seed Coats. Bot. Gaz., 56, 1913. 



16. Davis, W. E., and Rose, R. C. The Effect of External Conditions 



