506 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



The sublimate crystals, under a cover glass, are slowly soluble in cold 

 water; very soluble in warm water, alcohol, ether or acetone. From 

 the latter solution, hydrochinon crystallizes in prisms. The crys- 

 tals are furthermore colored reddish-brown with ammonia water, and 

 light green with a solution of ferric salts. 



Constituents. A neutral, tasteless principle, chimaphilin, occur- 

 ring in golden-yellow needles; two glucosides arbutin and ericolin 

 (see Uva-Ursi); several other crystalline principles; a volatile oil; 

 tannin 4 to 5 per cent; calcium oxalate; ash about 5 per cent. 



UVA-URSI. Red Bearberry. The leaves of Arctostaphylos 

 Uva-Ursi (Fam. Ericaceae), a procumbent shrub indigenous to 

 Europe, Asia and the northern United States and Canada. 



Description. Obovate, spatulate, 18 to 30 mm. in length, 6 to 

 10 mm. in breadth; summit obtuse; base acute, tapering; margin 

 entire, slightly revolute; upper surface dark green, glabrous, finely 

 reticulate; under surface yellowish-green; petiole about 3 mm. 

 in length, slightly pubescent; texture coriaceous, brittle; odor slight; 

 taste slightly bitter, astringent. 



INNER STRUCTURE. See Fig. 215. 



Arbutin is localized in the loose mesophyll and palisade layers 

 of the leaves and in the sub-epidermal layers of the petioles and 

 stems. Its presence may be determined by the use of nitric acid, 

 which colors the cells bright yellow or dark orange, the color gradually 

 fading. Vanillic acid colors the cells bright red, distinguishing it 

 from the leaves of Vaccinium myrtillus. Sections of leaves of Uva- 

 Ursi are colored bluish-black, with freshly prepared solutions of fer- 

 rous sulphate, distinguishing them from the leaves of Vaccinium Vitis- 

 Idaea. The presence of arbutin may also be determined in the leaves, 

 by the methods of microsublimation already given under Chimaphila. 



Powder. Yellowish-green to olive-green ; fragments of polygonal 

 epidermal cells associated with broadly elliptical stomata, about 0.035 

 mm. in length, surrounded by 5 to 8 neighboring cells ; cells of meso- 

 phyll with chloroplastids and frequently irregular masses of a car- 

 bohydrate ; fragments of fibrovascular bundles having spiral tracheae, 

 and narrow, strongly lignified sclerenchymatous fibers, frequently 

 also associated with crystal fibers having monoclinic prisms, from 

 0.006 to 0.015 mm. in diameter; numerous fragments made up of 

 cells having a yellowish-brown content which are colored a bluish- 

 black upon the addition of a freshly prepared solution of ferrous sul- 

 phate. 



Constituents. Two glucosides arbutin and ericolin; a crystal- 

 line, resinous principle, ursone; tannin about 5 per cent; gallic acid; 



