Heartwood formation in living stumps of Douglas-fir

Summary An anatomical and chemical examination was made of living stumps of Douglas-fir. Changes in heartwood and extractives formation are not significant under the conditions of severe physiological stress that existed unless cell morphology was also altered. It is proposed that the factors controlling the amount and composition of heartwood extractives are incorporated in the ray cells during the early stages of their development.The authors are particularly grateful to Mr. J. Walters, Director of the Research Forest and to Professor J. A. F. Gardner, Dean of the Faculty of Forestry, of the University of British Columbia, Canada for their considerable help in the collection and transport of the samples of living stumps which formed the basis of this investigation. They are also grateful to Mr. A. Ceselli, Mrs. J. Juricskay and Miss D. Muston for assistance in the anatomical studies.