50 PLANTING BULBS AND TUBERS* [chap. iii. 
is to say, he fixes them firmly in the ground, 
and covers them, but not so deeply as to 
exclude the air. In preparing a bed for hy¬ 
acinths or other tunicated bulbs, it is neces¬ 
sary to pulverize the soil to a much greater 
depth than for ordinary seeds; as the fibrous 
roots of the hyacinth descend perpendicularly 
to a considerable depth, as may be seen 
when these plants are grown in glasses. 
The very circumstance of growing hyacinths 
in glasses, where they vegetate and send 
down their roots exposed to the full influ¬ 
ence of the light, appears contrary to the 
usual effects of light on vegetation; and 
indeed the plants are said generally to thrive 
best, when the glasses are kept in the dark 
till the roots are half grown. However this 
may be, it is quite certain that hyacinths 
in glasses should never be kept in darkness 
when their leaves begin to expand; as, if 
there be not abundance of light to occasion 
rapid evaporation from the leaves, the plants 
will soon become surcharged with moisture 
from the quantity constantly supplied to their 
roots; and the leaves will turn yellow, and 
look flaccid, and unhealthy, while the flowers 
