316 SCIENCE FROM AN EASY CHAIR 



root-cuttings, and it is interesting to note that the hop- 

 grower finds that it is not desirable to allow the female 

 flowers to be fertilised, since, although the hops weigh 

 more after the setting of the seed, the valuable extractive 

 substances contained in the flower are diminished, used 

 up in the growth of the seed. Hence, often only one 

 male hop-vine to every 200 female hop-vines is allowed in 

 a hop-garden. 



It does not follow because a plant is a native of a given 



FIG. 55. Early winged female hop-louse, produced viviparously by the 

 first generation of daughters of the "Foundress," Fig. 58. These 

 winged females migrate from the plum tree, where they were born, to the 

 hop-vines by aid of their wings, and produce viviparously the form drawn 

 in Fig. 57. 



country that it can be easily cultivated anywhere in that 

 country, or that its finest cultivated varieties will be 

 hardy. Only a few limited territories (owing to the 

 nature of the soil, climate, and exposure) in Germany 

 (chiefly in Bavaria), and in Kent, Sussex, Worcestershire, 

 and Herefordshire, seem to be really favourable to hop- 

 growing in Europe. Certain parts of the Pacific coast of 

 the United States have of late years proved a very 

 successful ground, although hops were introduced from 

 Europe and first cultivated with considerable success in 



