280 
INDEX. 
V. 
Valleys, from their dampness and coldness, 
unfit for the naturalization of plants, 37 
Vegetable food, obtained mainly from the atmo- 
sphere, 129 ; alkalies a prime source of, 154 
Vegetable life, reciprocal influence of animal 
and, 106 
Vegetation, its elements, 55 
Ventilation of plant-houses, principles to be at- 
tended to in the, 258 ; its importance in 
winter, 24, 4T, 72, 144, 168, 240 
Virgin soil, its exciting effects accounted for, 154 
W. 
Walls prejudicial in some parts of greenhouses, 
232 
Watering plants, rules for, 119 
Water, component parts of, 129, 177; its 
agency on vegetation, 177; not a solvent of 
the earthy substance of manures, but of the 
gases evolved by them, 178 ; what gives it soft- 
ness, 179 ; advantages of that produced by 
rain, 179 
Weather, kinds of work to be done in particular, 
during winter, 263 
Weeping Willow, places in which it should be 
planted, 162 
Winds, advisability of screening tender plants 
from cold ones, 71 
Witsenia maura, 221 ; its management, 222 
ZicHYA, peculiarities of the genus, 147 
— pannosa, 1 47 ; culture of, 148 
LONDON : 
BKADBURY AND BVANS, PRINTERS, WHITJEFRIARS- 
