672 Forestry Quarterly 



leaf pine and Douglas fir, Miss Gerry (J) comes to the following 

 conclusions : 



1. In any cross-section the fibers nearest the pith are shorter, 

 there is a gradual (irregular) increase in length from the first 

 annual ring outward. 



(a) No constant length is found. 



2. In 26 specimens taken at from 2J^ to 3 inches from the pith 

 at four-foot intervals from butt to top there was a gradual 

 increase in length for about two thirds the height of the tree. 



3. No direct relation between length of fiber and strength could 

 be determined. 



(a) From butt to top specific gravity and strength decreased 

 but average fiber length increased. 



{h) Late wood was found to be about twice as strong as early 

 wood, although fiber was some 12 per cent shorter. 



(c) In "rothholz" the wood is stronger but fiber length shorter 

 than in normal wood. 



4. General range of variation in fiber length is not greater within 

 the species than in the individual tree. 



5. Longest fibers are in the earliest spring wood, shortest in 

 last layers of late wood. 



6. Root fibers have length equal to or greater than stem fibers. 

 Mell (4) states the following : 



L The average length of tracheids increases within the plane 

 perpendicular to the axis from the center outwards until the tree 

 reaches its maximum height growth, after which it remains quite 

 constant. 



2. The average length of tracheids increases from base until a 

 maximum is reached, after which it decreases toward the top, 



3. The length of Douglas fir fiber, based on measurements from 

 different parts of trunk and branches, is: average 2.68 mm, 

 maximtmi 3.30 mm, minimum 1.82 mm. 



