MORPHOLOGY OF WOOD 



241 



weakening effect of the storage rays, the vohimetric data here shown 

 indicate an almost complete inverse ratio to that of the thickness of the 

 lignihed walls and the specific gravity. 



Table l.—Taxod'mm disticlium (L.) Rich. Measurements in millimeters. 



Brashness has so many times been considered to be due to short 

 tracheids or fibers that special attention was paid to this phase of the 

 problem and the general results obtained hardly justify such an as- 

 sumption. To be sure there is in the case of Taxodium, as mentioned 

 in the t&ble, an appreciable difference in the average which favors such 

 a view, but later examples will show that brash woods often have even 

 longer fibers than strong specimens of the same species. This idea is 

 also supported by comparative lengths of fibers in different woods. 

 Figure 7 shows diagramatically the relative length and breadth of the 

 strengthening elements in the three woods mentioned. The longest 

 one represents a spring tracheid of Taxodium distichnm and measure- 

 ments will show that the length is about eighty times the diameter, 

 twice as long as are the fibers of Liriodendron, and four times as long 

 as those of Fraxlnns amcricana ; figures which do not argue well for 

 a relationship between short fiber length and brashness. 



Another reason opposed to the above view is that the radial rows of 

 cells do not end in the same horizontal plane but overlap as can be seen 

 by a reference to any tangential section of coniferous wood. Conse- 

 quently any weakness due to an interlocking of the tracheids would be 

 uniformly distributed throughout the stick rather than restricted to 

 some particular zone. Observations by Miss Gerry on the relation of 

 fiber length to strength of timber show a similar lack of affinity.^ To 

 quote direct: "The relation between the fiber length and the strength 

 values of the wood was indeterminate ; no direct eft'ect dependent on 

 length alone could be found." 



' Gerry, Eloise. Science N. S., Vol. XLI, No. 1048, January 29, 1915. 



