Douglas Fir Fiber 689 



The length rapidly increases to about 4 mm until about 50 rings 

 are added and thereafter increases very slowly, if at all. Con- 

 trary to the conclusions of Bailey and Shepard referred to above, 

 we find no marked decrease after about 50 years from the pith, 

 although this condition does sometimes occur. Considering only 

 that wood over 50 years from the pith, both the individual rings 

 measured and the average of all, show, in general, the fiber length 

 to be longest at 42 feet from the ground and gradually decreasing 

 from that point toward the top and the butt. {See Fig. 2.) Thus 

 it would appear that the fibers in the top and butt logs would be 

 shorter than those of the main trunk between these two. Except- 

 ing for the wood up to 40 feet from the ground, it appears that 

 the older the wood the longer will be the fiber, and it might almost 

 be stated that as a general rule a log having a great mmiber of 

 annual rings could be expected to show longer fibers than a similar 

 log having few annual rings. 



Table IV shows the location in siimmer or springwood of each 

 annual ring of the maximtun, minimum and of the average longer 

 fiber. Of the 112 rings in which these were determined, as is 

 shown at the end of the table, the maximum fiber was in the sum- 

 merwood in 96 rings, in the springwood in 16 rings; the minimum 

 fiber was in the summerwood in 35 rings and in the springwood in 77 

 rings ; the average of all fibers was longer in the summerwood in 62 

 rings, longer in the springwood in 8 rings, and equal in both spring 

 and summerwood in 42 rings. It would, therefore, appear that 

 the fiber of the simimerwood is longer than that of the spring- 

 wood in this particular tree, but it would not be safe to state this 

 as being the general condition, especially as contrary results, as 

 mentioned above, have been found by other investigators. 



The average longer fiber in the respective discs occurs, as is 

 shown by + in Figure 1, in the last annual ring in ten instances, 

 in the twentieth ring from the periphery in one instance, in the 

 fortieth ring in three cases, in the sixtieth ring in five cases, and 

 in the eightieth ring in two cases. In disc J at 42 feet from the 

 ground the average fiber at 80 rings from the periphery was the 

 same as in the last annual ring. Beyond the fact that the average 

 longest fiber occiu's most frequently near the periphery, but that 

 this condition does not occur constantly, there seems to be no 

 chance for any general conclusions in regard to the location of the 

 average longer fiber in the discs at different heights from the 



