12 FUSTIC WOOD: ITS SUBSTITUTES AND ADULTERANTS. 



ANATOMICAL CHARACTERS OF FUSTIC WOOD. 



A full description of the microscopic structure of fustic wood is 

 presented here for the help it may give in distinguishing true fustic 

 from possible new, and at present unknown, substitutes whose gross 

 characters may not, as in the case of the osage orange, smoke-tree, 

 and prickly ash, suffice for identification. 



Fustic wood does not exhibit true annual rings of growth. The 

 alternating bands of wood parenchyma and wood fibers are some- 

 times mistaken for such, the softer tissue appearing as early wood 

 and the dense tissue as late wood. This error may be avoided, how- 

 ever, by remembering that early wood is never composed of tissue 

 wholly different from that of the late wood. Moreover, the absence 

 of an intermediate zone showing gradual transition from early to late 

 wood is further evidence that these are not annual rings of growth. 



A radial cut of true fustic wood made with a sharp knife shows 

 alternating tangential bands of different tissues, which are quite con- 

 spicuous when viewed with a hand magnifier. Their prominence is 

 due not so much to the difference in color as to the variation in 

 density and character of the elements composing them. The main 

 tissue, consisting of very hard, thick-walled wood fibers, forms 

 dense undulating bands alternating with layers of less dense tissue 

 composed of thin-walled wood-parenchyma fibers, and known as 

 wood-parenchyma bands. These are seldom continuous around the 

 stem or branch, but are very irregular, often quite short or meeting 

 with the next inner or outer bands of similar tissue. They are from 

 one-third to one-half the width of the bands of wood fibers alternating 

 with them. The bands of wood fibers vary from 2 to 6 cells in width, 

 except in regions of pores, where they are often from 10 to 12 cells 

 wide. The pores lie within the bands of wood parenchyma and are 

 wholly surrounded by them. 



Vessels (transverse section) 1 vary from 0.02 to 0.25 millimeter in 

 diameter, are more or less evenly distributed throughout the wood, 

 and are easily seen with the aid of a pocket lens magnifying from 4 

 to 6 diameters. The walls are usually quite thick, especially on the 

 side bordering other vessels. The vessels are wholly surrounded by 

 wood-parenchyma fibers, and usually are much greater in diameter 

 than the average width of the bands, which are thus rendered undu- 

 lating. They are regularly distributed either singly, or less often in 

 radial groups of 2 to 4. and are invariably filled with a yellowish 

 mass called tyloses, which forms a network of cross walls within the 

 vessel cavities. The vessel segments, Which may, with aid of the 

 microscope, be seen in longitudinal sections or in macerated mate- 

 rial, are exceptionally short, seldom more than 0.5 millimeter long. 



i See description (.fig. 1). 



