NATURAL CONDITIONS OF PLANTS. 
7 
which trailed down between the model and the 
window, and were nearly without light, never 
produced either flowers or fruit, and the leaves 
were not more than one-tenth of the ordinary 
size. This specimen was exhibited to the Chan- 
cellor of the Exchequer,* to prove to him the 
depressing effects of want of light — and want 
of light alone — as all the other conditions of 
the plant were the same. Some fairy roses, 
which had flourished in a case standing in the 
open air for seven or eight years, were nearly 
killed by being placed in a dark part of the 
transept of the Great Exhibition for six or 
seven weeks ; this temporary deprivation of 
light doing more inj ury than all the variations 
of our climate for so long a period had been 
able to effect. Light also, by sustaining the 
vital energies of a plant, enables it to resist the 
depressing effects of cold. The secretions of 
plants, too, are always developed in greater 
perfection according to the intensity of the 
light (combined with heat), and this to such 
a degree that the same species of plant - — 
e.g. Cannabis sativa — which is inert in a 
temperate region, produces, in the tropics, secre- 
tions of a powerful and dangerous character. 
* Upon the occasion, in 1850, of a deputation waiting on the 
Chancellor for the abolition of the window duties. 
