QUASSIA. 151 



show a small one-half inch thick rind. Within is 

 seen the strongly marked whitish yellow woody centre, 

 which shows concentric sheath and narrow vessels and 

 very fine, closely arranged whitish medullary rays. A 

 light brown pith is found in the centre. 



With the higher magnification the cortex shows a layer 

 of cork, on cross-section oblong quadrangular, on long sec- 

 tion somewhat elongated hexagonal. Within is found a 

 layer of parenchymatic cells rich in calcium oxalate, also a 

 number of stone cells, which at times form a more or less 

 complete sheath separating the outer from the inner cor- 

 tex. The phloem of the fibro-vascular bundles consists of 

 a few bast fibres, sieve tubes, and parenchyma. They are 

 radially arranged and separated by the medullary rays, 

 which have become somewhat wider than when in the 

 xylem portion of the bundle. 



The medullary rays are small, one or two cells wide 

 only. The xylem contains ducts, woody parenchyma, 

 and simple parenchyma. 



The woody tissues lie in more or less alternate rows of 

 two or three pitted vessels surrounded by woody fibres and 

 one or two rows of woody parenchyma, pitted with simple 

 pores. There are no annular rings, as the plant is tropical. 

 Pith is composed of polyhedral cells. 



Differences. — Surinam, smaller pieces, branches, etc. ; 

 Jamaica, blocks, etc. 



Surinam, medullary rays one cell wide or only two. 

 Vessels smaller. Sheath of parenchyma in wood one or 

 two cells wide. Smaller sized pieces, never over four 

 inches in diameter. Thin, brittle bark. Denser wood. 

 Crystals present in woody parenchyma (Meyer). 



Jamaica, rays two or three cells wide. Vessels double 

 the size. Woody parenchyma two to four cells wide. 

 Large blocks. More open and porous. Crystals in 

 woody parenchyma and medullary rays. 



Chemistry. — The main and important constituents of 



