502 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



and umbelliferon. The fruits of Cicuta yield from 3.8 to 4.8 per cent 

 of a volatile oil, having an odor resembling chenopodium. They 

 also contain a volatile alkaloid, resembling coniine, which is said 

 to be present in the stems and leaves. 



CORNACE^:, OR DOGWOOD FAMILY 



A small family of shrubs and trees, comprising 85 species. The 

 leaves are simple or opposite, and the flowers are arranged in cymes 

 or heads, which in the case of the flowering dogwood (Cornus florida) 

 are subtended by 4 large, petal-like, white or pinkish bracts. Among 

 the histological characters, the following may be mentioned. The 

 pericycle contains either isolated groups of bast fibers or it is made up 

 of a composite and continuous ring of sclerenchyma. The tracheae 

 possess very narrow lumina and are marked by scalariform perfora- 

 tions. The walls of the wood fibers possess either simple or bordered 

 pores. The medullary rays are from 1 to 5 cells in width. Secre- 

 tory elements are seldom present, although in Nyssa secretory cells 

 occur in the leaves, and in Mastixia secretory canals are found in the 

 pith. The epidermal cells of both leaf surfaces are provided with 

 papillse, and the walls are sometimes metamorphosed to mucilage. 

 A distinct hypodermal layer is not infrequently developed beneath 

 the upper surface of the leaf, and occasionally special idioblasts, 

 containing crystals are developed. Calcium oxalate is usually 

 secreted in form of rosette aggregates, solitary crystals, or micro- 

 crystals. The non-glandular hairs- are mostly unicellular and are 

 sometimes provided with verrucose thickenings of the cuticle. 

 Glandular hairs of a number of special forms are present. 



CORNUS. Dogwood Bark. The bark of the flowering dogwood, 

 Cornus florida (Fam. Cornacese), a small tree quite common in dry 

 woods of the eastern United States and Canada, producing in the 

 spring, clusters of small flowers surrounded by an involucre, consisting 

 of 4 corolla-like bracts; and in the fall a cluster of scarlet, drupaceous 

 fruits. The bark of both the stem and roots is used to a limited 

 extent in medicine and was employed, during colonial times, as a 

 substitute for cinchona. The root bark is preferred. It is usually 

 collected in the fall and carefully dried. 



Description. Root bark, in quills or transversely curved, chip- 

 like fragments, from 0.5 to 5 cm. in length, 0.5 to 1 cm. in width, bark 

 1 to 4 mm. in thickness; externally dark or reddish-brown, longitu- 

 dinally furrowed, more or less scaly, and occasionally transversely 

 fissured; inner surface pinkish- or purplish-brown, distinctly striate, 



