MEASUREMENTS OF WOOD FIBER 



H. S. CONARD AND W. A. THOMAS. 



Many of the properties of wood depend upon the character and 

 arrangement of the fiber cells which enter into its composition. This 

 is especially true of those properties which determine its strength, 

 hardness and adaptability for the manufacture of paper pulp. With 

 a view to throwing light on these properties, we have made 

 measurements of the length and diameter of the fibers in forty- 

 one species of trees. No attempt was made to segregate the various 

 types of fiber that occur in different species. We have taken any of 

 the slender, fusiform, non-septate, thick walled members of the 

 xylem. The maximum and minimum figures indicate that this 

 lack of discrimination has not introduced any serious error. Were 

 very critical discrimination attempted, the comparison of species 

 would prove unduly complex, if not impossible. 



Our material was obtained partly from local lumber dealers, 

 partly from the Grinnell College collection of wood specimens, and 

 partly from fresh material cut from the College botanic garden and 

 campus, and from neighboring groves. It was mostly heart wood, 

 though not in every case. This should not aff'ect the measurements. 



Shreds of the wood about two millimeters in diameter were 

 split off and placed in test tubes of strong commercial nitric acid. 

 To each tube is added about 0.5 gm. of potassium chlorate. The 

 maceration is carried on for about thirty hours at 35 to 40 degrees 

 centigrade. The acid is then poured off. The wood is washed in 

 several changes of water extending over four to six hours. The 

 resulting fragments are usually nearly colorless, and the constituent 

 cells are readily separated by teasing or by more or less violent 

 shaking in water. A drop of a suspension of the separated cells 

 is then placed on a slide, covered, and the fibers are measured 

 with an eye-piece micrometer. Some specimens were stained in 

 safranin, dehydrated, and mounted in balsam as permanent prepa- 

 rations. A few species of wood were softened in hydrofluoric acid 

 and sectioned in the three usual planes. These served as checks 

 on the macerated material, but were much less satisfactory for 

 purposes of measurement, especially measurement of length. Only 



