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. 



Flo. 1.5.3. — Hops (Hamulus Lupulus, Mulberry Family, Moracea). 1, branch 

 bearing staminate flower-cluster. 2, branch bearing pistillate flqwer- 

 clu,sters, and leaves. S, pistillate flower-cluster. 4, two pistillate 

 flowers and their bract. S, 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 yea.st (which occurs naturally on the 

 surface of the fruit) to produce alcoholic fermentation of the 



