290 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



Powder. Dark green; calcium oxalate in monoclinic prisms 

 0.007 to 0.035 mm. in diameter, frequently in crystal fibers; non- 

 glandular hairs 1-celled, about 0.5 mm. in length, more or less curved, 

 thick-walled, with yellowish-brown contents, arranged in groups of 



2 to 15, and spreading from the base; numerous cells of loose 

 mesophyll with irregular tannin masses; sclerenchymatous fibers 

 thick-walled, lignified and with simple pores. 



Constituents. Volatile oil; a bitter principle; tannin, about 



3 per cent; gallic acid, and calcium oxalate. 



The distillate, obtained on distilling either the fresh or dried 

 leaves of Hamamelis with water, contains an aromatic substance 

 that apparently does not exist as such in the leaves. The sub- 

 stance sold as hamamelin is a mixture consisting of an evaporated 

 alcoholic extract of either the leaves or bark, that of the former 

 being greenish-black and more permanent and the latter brownish- 

 black and more or less hygroscopic. 



HAMAMELIDIS CORTEX. Witchhazel Bark. The bark and 

 twigs of Hamamelis virginiana (Fam. Hamamelidacese), a shrub 

 indigenous to Canada and the United States and extending west to 

 Minnesota and south to Texas. 



Description. Bark is transversely curved pieces 5 to 20 cm. in 

 length, 5 to 15 mm. in diameter, bark 0.5 to 1 mm. in thickness; 

 usually with the grayish-brown or reddish-brown periderm removed, 

 outer surface light brownish-red, smooth; inner surface light reddish- 

 brown, longitudinally striate; fracture short-fibrous; odor slight; 

 taste astringent. 



Twigs 2 to 5 mm. in diameter; the outer surface varying in color 

 from yellowish-brown to blackish-brown, smooth or somewhat scurfy, 

 longitudinally wrinkled, and with numerous small lenticels; small, 

 twigs somewhat zigzag from numerous leaf -scars; bark thin, easily 

 separable from the whitish, hard, radiate wood; pith small. 



Inner Structure. (Fig. 130.) A layer of phelloderm consisting 

 of from 10 to 15 rows of cells with yellowish-brown contents; outer 



dermis; Sc, sclereids or colorless stone cells (also called idioblasts); N, loose 

 mesophyll; in figures a and b the palisade and pneumatic tissue are shown 

 with thick-walled stone cells, branched in a, penetrating epidermis in 6; 

 in c one end of a sclereid is entering an epidermal cell, and in d, is shown a 

 surface view of the epidermis with the end of a stone cell. D, basal portion 

 of a 4-branched hair from the dorsal epidermis of leaf, showing very thin 

 cross-walls in the branches. E, surface view of dorsal epidermis of leaf- 

 blade, showing the stomata (S) and oil globules (0). F, transverse section 

 of a midrib from near the summit of the leaf-blade, letters as in A. After 

 Holm, Merck's Report, 1912, p. 5. 



