694 Forestry Quarterly 



Resiilts of examination of one disc each of 4 trees, two being 

 typical coast Douglas fir and two being the mountain form, are 

 recorded in Table V and Figures 8, 9, 10, 11. A disc of tree 5 of 

 shipment 2 taken at 19 feet from the ground gave 3.49 mm, as an 

 average fiber length of 500 measurements made from ten annual 

 rings. Comparing this with the average for tree 1 of the same 

 shipment, i. e., from the coastal region, at 18 feet from the ground, 

 we find this latter tree gives an average of 4.43 mm for the same 

 number of measurements. The indication from this is that 

 the fiber length as stated for shipment 2, tree 1 is possibly above the 

 general average for all trees of the coastal region of British Colum- 

 bia. Both trees at the height from the ground given show a 

 marked increase in fiber length up to 60 years from the pith fol- 

 lowed by increases and decreases within comparatively narrow 

 limits until near the periphery, when a marked decrease occurs. 

 As is shown above, this decrease near the periphery does not hold 

 throughout a complete tree. The discs of shipment 3 from the 

 mountain region of British Columbia taken from trees 8 and 10 

 at 19 feet from the ground give average measurements of 3.06 mm 

 and 4.18 mm respectively. The disc from tree 8 (Fig. 8), con- 

 tained only 140 annual rings and fiber, shows an increase in length 

 practically up to the periphery, but tree 10 (Fig. 9) with 169 

 annual rings shows a decrease near the periphery. In both, as is 

 the case in all discs measured, the increase up to about 50 years is 

 very rapid but is followed by irregular, small increases or de- 

 creases. Comparing the coastal forms with both the mountain 

 forms it appears that the former produces a somewhat longer 



fiber. 



Summary 



1. Measurements of 8550 tracheids at 171 points in a single 

 Douglas fir tree showed the average fiber length to be 4.46 mm, 

 the maximiun fiber 8.60 mm, and the minimtmi 0.34 mm. 



2. The length of the tracheids increases rapidly up to about 50 

 years from the pith, after which there are comparatively small 

 and irregular increases or decreases, with an average slight increase 

 toward the periphery. 



o. The most marked decrease near the periphery occurs near 

 the butt. 



3. The average fiber length increases up to somewhat less than 

 one third the height measured and then gradually decreases. 



