PREFACE 



Acknowledgment is made to Dr. F. E. Clements for assistance in 

 planning the laboratory work and to Professor J. P. Wentling, under 

 whom the sylvicultural work was done, for many suggestions in the 

 development of the study and in the interpretation of the data. The 

 author is indebted to the United States Forest Service for the investi- 

 gations he conducted while at the Priest River and Wind River Experi- 

 ment Stations, especially to Mr. D. R. Brewster for his help at the Priest 

 River Experiment Station. All plates are original except Plates I and II, 

 for which credit is given the United States Forest Service. 



JULIUS V. HOFMANN 

 March 1, 1914 



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