154 PLANT ORGANS OR PARTS OF PLANTS. 



The former are irregular, heavy, deprived of bark and 

 sap-wood, I m. to 1.5 m. long, 12 to 15 cm. thick, the 

 surface from exposure dark-brown, with a slight greenish 

 tint, internally deep red. The wood is firm, fibrous, 

 susceptible of a high polish, but easily split. It is odor- 

 less and tasteless and does not color water. 



Histology. — The wood on cross-section reveals al-. 

 ternate bands of dark, dense, and shining tissue and 

 lighter and porous circles. A radial longitudinal section 

 shows a peculiar structure characterized by the oblique 

 directions in which the alternate bands run, crossing each 

 other at an angle of 30 degrees. The wood is divided 

 radially by numerous fine medullary rays into narrow 

 bands. 



The wood fibres of the dense bands are long, varying 

 much in diameter, their deep red thickened walls leaving 

 small round or oval lumens. 



The light porous bands are composed of two to eight 

 rows of slightly thickened cubical pitted parenchymatic 

 cells containing large crystals of calcium oxalate and 

 masses of red resin. Imbedded in this tissue are the 

 large pitted walled vessels, single or in couples, often 

 occupying all the space between the medullary rays. 

 They are often filled with red resin. The medullary rays 

 are a single cell wide, rarely two-celled, and vertically 

 five to eleven cells high. Their outer ends are curved. 



Powder. — The powder is dark red, odorless and taste- 

 less, colored bluish-red by alkalies. It consists mostly 

 of wood fibres, but with some pains portions of the 

 closely pitted vessel walls and fragments of tissue showing 

 tangential sections of the medullary rays may be found. 

 These being but one cell row in width, distinguish this 

 from all other red woods (Moeller). Calcium oxalate 

 crystals are also present. 



Chemistry. — Santalic acid or santalin is the principal 

 constituent. Further, pterocarpin and santal and homo- 



