CRUDE DRUGS. 525 



Inner Structure. — See Figs. 229a, 304. 



CoN.STiTUENTS. — The nature of the active constituents of this 

 drug is not known. It may contain the glucoside cascarin (pur- 

 shianin), which on hydrolysis yields emodin and one or more 

 active principles ; and the neutral principle chrysarobin, which 

 yields chrysophanic acid (see Rhubarb). The bark apparently 

 contains emodin ; isoemodin, a principle which is isomeric with 

 emodin, insoluble in ammonia and resembles a similar principle 

 in Frangula ; a principle which yields on hydrolysis syringic acid ; 

 a fat consisting of rhamnol arachidate ; a bitter principle ; several 

 resins ; tannin ; glucose ; starch ; calcium oxalate ; and ash about 7 

 per cent. 



Adulterants. — Rhamnus californica, a shrub indigenous to 

 Southern California and the neighboring States, yields a bark 

 which closely resembles that of Rhamnus Purshiana, but may be 

 distinguished from it by the medullary rays, which are from 3 to 5 

 cells wide, and occur in more or less parallel wavy rows, and by 

 the distinct crenation of the inner margin of the bark. 



Allied Plants. — The fruits of Rhamnus cathartica, a shrub 

 indigenous to Central and Southern Europe and Asia, are used 

 xmder the name of Buckthorn berries. They are globular, about 

 5 mm. in diameter, greenish-brown or black, and consist of four 

 i-seeded nutlets ; the seeds are dark brown and triangular-convex. 

 The odor is slight but disagreeable. The taste is bitter and acrid, 

 the saliva being colored yellow. The fruits contain a glucoside, 

 rhamnonigrin, which yields emodin ; a bitter principle ; and three 

 yellow coloring principles, viz. : rhamnocitrin, rhamnolutin and 

 rhamnochrysin. 



The fruits of Rhamnus cathartica, as well as of R. infectoria 

 (known as French Berries) and of R. sa.vatilis (called Persian 

 berries) have been used as yellow dyes. The fruits of several 

 species growing in China yield a green indigo. 



VIBURNUM PRUNIFOLIUM.— BLACK HAW BARK. 

 The dried bark of the root of Viburnum prunifolium or of T 

 Lentago (Fam. Caprifoliacese), shrubs (Figs. 179, 230) indig- 

 enous to the Eastern and Central United States (p. 382). The 

 root bark is more highly esteemed than that of the stem and 

 branches. 



