CRUDE DRUGS. 551 



Description.^ — Oblong or ellipsoidal, 2 to 4 mm. long, i to 

 1.5 mm. in diameter; involucre ovoid, consisting of twelve to 

 eighteen closel)' imbricated, ovate or ovate-lanceolate, glandular, 

 somewhat shiny bracts, about 2 mm. long, with a yellowish-green 

 or greenish-brown middle portion and whitish margin ; torus flat, 

 naked, with three to six unexpanded, perfect tubular flowers 

 about 1.5 mm. long and completely inclosed by the upper bracts; 

 ovary oblong ; pappus wanting ; odor distinct ; taste aromatic. 



Inner Structure. — SeeFig. 240. 



Constituents. — A crystalline neutral principle, santonin, 

 which occurs to the extent of 2 to 3.5 per cent, just before the 

 expansion of the flowers ; volatile oil about 2 per cent., consisting 

 chiefly of cineol; a crystalline principle artemisin, which is appar- 

 ently oxysantonin ; and a resin. Santonin crystallizes in rhombic 

 prisms, becoming yellow on exposure to light ; it is nearly insoluble 

 in water, sparingly soluble in alcohol ; and colored red by alcoholic 

 solutions of the alkalies. 



Allied Plants. — Artemisia gallica, a plant abundant in 

 France, contains santonin and about i per cent, of a volatile oil. 



ARNICA.— ARNICA FLOWERS.— The dried, expanded 

 flower-heads of Arnica montana (Fam. Compositse), a perennial 

 herb (p. 394) indigenous to Central Europe, and growing in the 

 movmtains of Switzerland, Asia and Western North America. 

 In Germany, on account of the involucre and torus being injured 

 by the larvae of the insect Trypeta arnicivora, these parts are 

 removed and the florets alone used. 



Description. — Sub-globular or truncate-conical, about 15 

 mm. in diameter ; involucre campanulate, bracts twenty to twenty- 

 four in two rows, linear-lanceolate, dark green, pubescent, gland- 

 ular ; torus solid, slightly convex, deeply pitted, bristly hairy ; ray 

 or ligulate florets (Fig. 241, B), fourteen to twenty, about 2 cm. 

 long, bright yellow, pistillate, corolla 3-toothed, 7- to 12-veined, 

 very pubescent and glandular below, ovary about 4 mm. long, 

 erect, pubescent and glandular, pappus consisting of a single row 

 of about thirty rough bristles; cHsk or tubular florets (Fig. 241, 

 C), forty or fifty, about 17 mm. long, perfect, bright yellow, 

 corolla 5-toothed, very glandular and pubescent below, ovary about 

 6 mm. long, glandular and pubescent ; akene spindle-shaped, dark 



