362 SUBTERRANEAN ORGANS 



been sliced occur in cylindrical, conical, or barrel-shaped pieces 

 varying in size, but frequently from 7 to 10 cm. in length and 3 to 

 6 cm. in thickness, although of course they may be larger or smaller. 

 The larger rhizomes, which are usually cut longitudinally, yield 

 plano-convex pieces, frequently tapering more or less towards either 

 end ; such pieces often measure 8 or 10 cm. in length or breadth and 

 4 cm. in thickness. These two principal forms are known as ' rounds ' 

 and ' flats ' and are commonly sold in separate cases. They are 



FIG. 188. Chinese Rhubarb (Shensi flat), showing network 

 of whitish lines. 



frequently drilled, a piece of string being occasionally found in the 

 perforation. The outer surface is dusted over with a fine bright 

 yellow powder, and bears evidence of having been not only peeled 

 with a knife, but carefully dressed with a file or scraped after the 

 drug has been dried. Here and there small portions of a dark layer 

 may still be found. These characters are common to the commercial 

 varieties of Chinese rhubarb generally, but the following apply more 

 particularly to the finest variety, viz. Shensi rhubarb. 



If the outer surface, freed from the yellow powder that adheres to it, 

 is examined with a lens, a number of minute, longitudinal, dark reddish 

 brown lines and dots can be observed imbedded in a white ground mass, 

 which latter frequently forms a delicate network, in the meshes of 



