206 BARKS. 



(101) Sassafras Root Bark. 



The root bark of Laurus Sassafras, Linn. (N.O. Laurineee). 



The bark presents the following structure : 



(1) Cork, composed of large polygonal cells, with slightly 

 thickened, yellowish brown walls. 



(2) Phelloderm, the cells of which resemble those of the cork, 

 but are colourless and not suberised. 



(3) Cortex, consisting of polygonal cells with intercellular 

 spaces. These cells contain starch grains, which are either 

 simple or compound; the former are oval or rounded, and possess 

 a very distinct stellate or fissured hilum, the latter are com- 

 posed of two, three, or four grains which, when separated, 

 exhibit one or more flattened surfaces. The cortex also con- 

 tains large oil-cells filled with yellowish volatile oil. 



4) Bast Ring, which comprises the majority of the bark, and 

 is traversed by medullary rays one or two cells wide. Most of 

 the cells of the bast parenchyma have smooth walls, but many 

 are pitted. The bast rays contain numerous large oil-cells and 

 large, isolated, fusiform bast fibres, the walls of which are so 

 thick as to leave but very small cavities. The sieve tubes are 

 arranged in tangential bands, and in the outer part of the bast 

 ring are collapsed. 



The diagnostic characters of sassafras root bark are : 



(a) The oil-cells. 



(b) The large, thick-walled, isolated bast fibres. 



(c) The starch grains. 



(d) The parenchymatous cells, with pitted walls. 



