TRUE MAHOGANY. . Q1 
potassium and sodium hydroxides. The wood when boiled in a weak 
solution of the hydroxides yields a deep reddish-brown coloring 
matter. 
Wood fibers occur usually in distinct radial rows, from a few to 12 
or 15, between pith rays, and constitute the bulk of the wood. Near 
the pores this regular radial arrangement is often disturbed by their 
rapid growth. They are polygonal and have as a rule small lumina 
(celi cavities). They vary from 0.84 to 2.268, averaging 1.315 mill- 
meters in length, and are rarely more than 0.02 millimeter in 
diameter. Wood fibers are often found that have delicate transverse 
partitions (fig. 4, B), a character that has been frequently observed 
in other woods belonging to this family of trees. True wood fibers 
are sometimes mistaken for wood-parenchyma fibers, but they may 
be distinguished from the latter by the very sharp-pointed ends and 
the minute, simple, slit-like pits. The fact that the wocd fibers in 
mahogany are septate serves to distinguish true mahogany from a 
great many of its substitutes. 
The cells in the outer part of the annual rings of growth are espe- 
cially remarkable for their thickness and density. Ht is also notice- 
able that the cavities of the wood fibers in the early wood of samples 
from Florida and Cuba are larger than these formed later in the 
season. ‘The reason for this appears to be that the fibers with wide 
cell cavities in the early wood serve as carriers of sap, and there is, 
therefore, no need of large vessels for this purpose in the late wood. 
This is evidently not the case in wood from British Honduras. In 
wood of the latter type, which forms no such large cells in the early 
wood, there seems to be greater need of large vessels throughout the 
entire seasonal or annual layer of growth in order to transport the 
large supply of water these trees require, because there is practically 
no cessation in vegetative activity throughout the growth period. 
The distribution of the large vessels is, therefore, regular through- 
out. In the wood with large vessels the fibers have thinner walls, and 
the quality of wood may be judged or predicted from such structural 
characteristics. 
Wood-parenchyma fibers (fig. 4, A 0b) occur usually near the ves- 
sels and consist of from four to eight slightly elongated, thin-walled 
cells. Im transverse section these cells are polygonal in form; in 
longitudinal section they are perpendicularly elongated and have 
small round or oval pits on their radial and tangential walls. YWhere 
they are in contact with vessels the pits are larger and not infre- 
quently have a sight border. The individual cells contain an abun- 
dance of dense brown colocring matter similar to that found in pith- 
ray cells. A number of these fibers are made up of cubical cells with 
very thin walis, each cell being filled with a small crystal of calcium 
oxalate or calcium carbonate. ‘These crystal-containing fibers are es- 
