Douglas Fir Fiber 685 



maximum is 7.26 mm, and average minimum (always in the first 

 annual ring), 0.51 mm. Table 1 gives concisely the averages for 

 each 50 measurements taken throughout the tree as well as the 

 averages by discs and by rings. Since the rings were cut out every 

 20 annual rings from the periphery toward the pith, the first 

 annual ring varies from one to 19 years from the next ring measured . 

 As a resiilt in two cases (discs X and B') there is a measurement in 

 an annual ring very close to the pith as well as the first annual 

 ring and the former figures are omitted in making the higher 

 average in those cases where two are stated. The average omit- 

 ting this extra short measurement is probably more nearly the 

 actual average to be compared with the averages of other rings. 



Table II shows the maximum and minimum fibers as found in the 

 discs at different heights from the groiind; also as found in the 

 various annual rings and the averages for the latter. The maxi- 

 mum, 8.60 wm, for the tree, was in the twentieth annual ring from 

 the bark, or 145 years from the pith, at a height of 26 feet from the 

 ground. As is shown by X in Figure 1, the maximimi fiber of the 

 respective discs occurred in the annual ring nearest the bark in 11 

 cases in the twentieth ring from the bark in 4 cases, the fortieth 

 ring from the bark in 4 cases, in the sixtieth from the bark in 2 

 cases, and in the eightieth in 2 cases, the other rings no cases. In 

 disc J' at 146 feet from the ground a maximum was found in both 

 the fortieth and sixtieth rings from the periphery, in disc V at 90 

 feet from ground in the last and sixtieth rings, and in disc T in the 

 last and the fortieth rings. It will readily be seen that the annual 

 rings last formed have the longest fibers. The curve of average 

 maximimi fibers (Fig. 7) , is much like the curve for the average of 

 all fibers or the curve for any one annual ring, i. e., showing a sharp 

 increase nearer the pith and then a more gradual increase practi- 

 cally to the last annual ring. The increase in this case is, how- 

 ever, much more marked than is the case in Figures 3, 4, 5 and 6, 

 showing average for all fibers and typical curves at various heights. 

 The minimtmi fiber always occiirs in the annual ring first formed 

 and the curve for minimum fiber lengths in the different rings is 

 much the same as the maximum, except that there appears to be 

 a distinct, though small, decrease in the average minimum in the 

 annual rings after about 100 from the pith. 



As has already been stated, the fiber in the first annual ring 

 formed at any height is extremely short, averaging 1.12 mm. 



