ALCOHOLIC BEVERAGES AND STIMULANTS 157 
access of only pure air to the mixture), the fermentation will 
be stopped and the liquid will keep indefinitely. The killing 
or exclusion of yeasts and similar agents of decomposition 
from foods to be preserved is the secret of the process of 
“canning’’ or “tinning’’ meats, vegetables, and fruits. 
Fic. 153.—Hops (Humulus Lupulus, Mulberry Family, Moracee). 1, branch 
bearing staminate flower-cluster. 2, branch bearing pistillate flower- 
clusters, and leaves. 3, pistillate flower-cluster. 4, two pistillate 
flowers and their bract. 45, ripe cone-like fruit-cluster. 6, a single 
fruit. (Wossidlo.)—A twining perennial herb with rough stems, grow- 
ing 10 m. tall; leaves rough, hairy; flowers, greenish; fruit, straw- 
colored. Native home, Europe, Asia, and North America. . 
Wine is made by expressing the juice of grapes or other 
fruit and allowing yeast (which occurs naturally on the 
surface of the fruit) to produce alcoholic fermentation of the 
