CRUDE DRUGS. 537 



principle which on sublimation gives off an odor of coumarin ; 

 0.22 per cent, of an acrid resin; and 31 per cent, of a fixed oil 

 which absorbs oxjgen on exposure to air and is in the nature of 

 a drying oil. 



The barks of a number of other plants of this family are used 

 like that of Mezereum, as Daphnopsis Schzvartzii of the West 

 Indies, Lasiosiphon eriocephahis of India and Ceylon, and various 

 species of Stellera, Struthiola and Thymelaea. 



PRUNUS VIRGINIANA.— WILD BLACK CHERRY 

 BARK. — The bark of the stem and branches of Prunus serotina 

 Ehrhart (Syn. Prunus virginiana Miller) (Fam. Rosaceae), a 

 tree (Fig. 235) indigenous to the Eastern and Central United 

 States and Canada. The bark is collected in autumn, and should 

 be carefully dried and preserved in air-tight containers (p. 287). 



Description. — Usually in transversely curved pieces 2.5 to 8 

 cm. long, I to 5 cm. in diameter, 0.5 to 4 mm. thick; outer surface 

 light brown or greenish-brown, somewhat glabrous, with numer- 

 ous lenticels 3 to 4 mm. long ; inner surface light brown, longitud- 

 inally striate and occasionally fissured ; fracture short, granular ; 

 cork dark brown, thin, easily separable from the green phello- 

 derm, inner bark porous and granular; odor of the drug distinct, 

 and on the addition of water developing an odor of benzaldehyde 

 and hydrocyanic acid; taste astringent, aromatic. 



The bark of the trunk is dark brown and rough externally. 



Constituents. — A glucoside analogous to amygdalin or lau- 

 rocerasin; a ferment which resembles emulsin; these two princi- 

 ples yielding by interaction hydrocyanic acid and benzaldehyde; 

 also a glucoside which is crystalline, bitter and fluorescent ; tannin 

 2.5 to 4.5 per cent. ; gallic acid ; starch and calcium oxalate. 

 Amygdalin occurs chiefly in the inner bark and varies in amount 

 from 3.16 to 4.12 per cent, in the bark which yields from 0.23 to 

 0.32 per cent, of hydrocyanic acid. The root bark contains more 

 amygdalin than either the bark of young twigs or the trunk. 

 The latter may contain but 0.5 per cent, of amygdalin and yield 

 as little as 0.03 per cent, of hydrocyanic acid. The amount of 

 amygdalin present varies even in the bark of the same thickness 

 from the same tree. When the exposure is such that the chloro- 

 plastids are abundant in the cells of the bark, then the per cent. 



