SEEDS AND FRUITS. 319 



in a sack and carefully sifting; one ounce of glands may 

 be obtained from one pound of Hops. Hops are found 

 by analysis to contain volatile-oil (two per cent.), resin, 

 gum, malic acid, tannin, etc. The ash amounts to 8.5 

 per cent. By distillation with water the Hops yield nine 

 per cent, of oil. Hops are used in large quantities in 

 brewing beer and in medicine. The plant was introduced 

 into the United States about two hundred and sixty years 

 ago, but extensively cultivated only within the last 

 seventy-five years. In Sweden, a fibre is obtained by 

 boiling the Hop-plant in alkaline-water for a few hours, 

 then in acetic acid ; from it is manufactured a strong, 

 white and durable cloth. 



321. The Vanilla-plant, Vanilla planifolia, is a mem- 

 ber of the Orchid family {OrehidacecB). It is an epiphyte, 

 growing on trees in Tropical America, now cultivated in 

 India, East Indies, and elsewhere. It has thick, laurel-like 

 leaves and inconspicuous flowers. The fruit is a fleshy 

 capsule five or ten inches long; it is gathered before 

 maturity, wrapped in wool, and heated, then exposed ; this 

 process is often repeated till the fruit is dry, and the odor 

 and brown color in the meantime becoming fully developed. 

 Upon analysis the following constituents have been found : 

 tannic acid, resin, fat, wax, gum, sugar, and an aromatic 

 substance, namely, Vanillin. The flowers of the Vanilla- 

 plant when cultivated out of its native country must be 

 artificially fertilized. It is propagated by attaching scions 

 to trees, which produce fruit after three years, and continue 

 to bear thirty to forty years. Its culture is carried on in 

 connection with the culture of the Chocolate-tree, on which 

 the Vanilla-plant grows. 



322. Vegetable Ivory is the endosperm of Phytelephas 



