DOGWOOD 503 



with prominent lenticular elevations; fracture short; outer bark 

 light brown having yellowish stone cells, inner bark light purplish- 

 brown; odor slight; taste bitter and astringent. The stem bark 

 usually occurs in quills having externally a dark gray or reddish-brown 

 color and internally a thin, radiate, whitish inner bark. 



Inner Structure. Several layers of thick-walled pericambial cork, 

 having in the thinner pieces the remnants of an endodermis, the 

 outer walls of the latter being considerably thickened; primary cor- 

 tex of several layers of thin-walled parenchyma containing either 

 starch or tannin; inner bark of wedges of leptome and parenchyma 

 separated by starch-bearing medullary rays, 1 cell in width. The 

 stem bark is distinguished by the presence of solitary crystals of 

 calcium oxalate in the parenchyma cells of the cortex; and by the 

 presence in the inner bark of several interrupted circles of tangen- 

 tially elongated groups of bast fibers. The fragments of wood show 

 spiral tracheae, tracheids, and thick-walled wood fibers. 



Constituents. A crystalline bitter principle, cornin, which is 

 soluble in water and alcohol; a tasteless resin, insoluble in water 

 and soluble in hot alcohol; tannic acid, 3 per cent; gallic acid; and 

 an orange-colored fixed oil. The so-called cornin is a hydro-alcoholic 

 extract prepared from the drug and is a mixture of principles. 



Literature. Holm, Merck's Report, 1909, p. 318. 



ERICACEAE, OR HEATH FAMILY 



A large family of nearly 1500 species, mostly erect or prostrate 

 shrubs, occasionally small trees, or sometimes herbs, and of very 

 wide geographic distribution. The plants vary in their morphological 

 characters, the leaves being deciduous or evergreen, the flowers regu- 

 lar or nearly so, and the fruit a capsule, berry or drupe. The tracheae 

 usually have small lumina, and the walls are provided with either 

 scalariform perforations, bordered or simple pores. The wood 

 and bast fibers have as a rule bordered pores. Calcium oxalate is 

 secreted in the form of rosette aggregates or solitary crystals. Both 

 glandular and non-glandular hairs occur of a variety of forms. 



The family can be divided on morphological grounds into 3 sub- 

 families. 1. The ERICACEAE proper, in the flowers of which the 

 calyx is free from the ovary, and the stomata are surrounded by more 

 than 2 epidermal cells. This sub-family includes Rhododendron, 

 Kalmia, Epigsea, Gaultheria, and other heath-like plants. 2. The 

 VACCINIACE^E, or whortle-berry sub-family, in the flowers of which 

 the calyx adheres to the ovary, the latter developing into an edible 



