Douglas Fir Fiber 695 



4. The tracheids in a given annual ring increase in size from 

 the ground upwards until a maximum is reached and then decrease 

 to the top. 



a. The maximum length occurs higher from the ground in the 

 rings nearer the bark. 



b. The annual rings last formed give the longest average fiber. 



5. Measurements indicate that a greater growth in diameter 

 may be correlated with a shorter tracheid. 



6. A greater growth in height appears to be correlated with a. 

 longer tracheid. 



7. The tracheids in "rotholz" are shorter than those in "zug- 

 holz" of the same annual ring. 



8. Fiber length appears, in tree measured, to be somewhat longer 

 in the summerwood than in the springwood. 



9. Both fiber length and strength increase rapidly from the pith 

 outwards to a certain point, after which comparatively small 

 increases and decreases occiu" irregularly. No definite relation at 

 various height in tree could be established. 



10. Douglas fir from the coast region of British Columbia 

 appears to produce a fiber averaging slightly longer than that 

 growing in the mountains. 



Further studies are being conducted on spruce and pine and it 

 is hoped that comparisons with the data herein given will lead 

 to more definite establishment of certain of the conclusions stated 

 above. 



Literature Cited 



(1) Variation in length of coniferous fibers. Shepard, H. B., and Bailey 

 I. W. Proc. Soc. Amer. For. P:4, Oct., 1914. 



(2) Sanio's laws for variation in size of coniferous tracheids. Bailey, I. W., 

 and Shepard, Bot. Gaz. 60, 1, July, 1915. 



(3) Gerry, E. Fiber measurement studies: length variations, where 

 they occur and their relation to the strength and uses of wood. Science 

 Vol. 61, No. 1048, page 179, 1915. 



(4) Mell, C. D. The length of tracheids in the wood of cone-bearing trees. 

 Paper Trade Journal, 15 June, 1911, p. 52. 



(5) Penhallow, D. P. Anatomy of Gymnosperms, Boston, 1907. 



(6) Sanio, K. Jahrbucher d. Wiss. Botanik, Vol. VIII, p. 401, 1867. 



