THE DOGSBANE. 
63 
means of valves or contractions, the tube remaining 
open ; but the creature cannot crawl up by reason of 
the inverted spines, and to prevent its escape by flying 
up the tube, the flower makes an extraordinary curve, 
bending up like a horn, so that any winged creature 
must be beaten back by striking against the roof of this 
neck as often as it attempts to mount, and falling back 
to the bulbous prison at the base of the flower, dies by 
confinement and starvation, and there we find them : a 
certain number of these perishing, the blossom fades 
and drops ofl*. 
All the varieties of this snapdragon have the power 
of maintaining a state of vegetation in great droughts, 
when most other plants yield to the influence of the 
weather; and it is the more remarkable in these plants, 
as the places in which they chiefly delight to vegetate 
are particularly exposed to the influence of the sun. In 
that hot dry summer of 1825, when vegetation was in 
general burned up and withered away, yet did this plant 
continue to exist on parched walls, and draw nutriment 
from sources apparently unable to afford it; not in full 
vigor certainly, but in a state of verdure beyond any 
of its associates. The common burnet (poterium san- 
guisorba) of our pastures, in a remarkable degree, like- 
wise possesses this faculty of preserving its verdure, 
and flourishing amid surrounding aridity and exhaustion. 
It is probable that these plants, and some others, have 
the power of imbibing that insensible moisture, which 
arises from the earth even in the driest weather, or from 
the air which passes over them. The immense evapora- 
tion proceeding from the earth, even in the hottest sea- 
son, supplies the air constantly with moisture ; and as 
every square foot of this element can sustain eleven 
grains of water, an abundant provision is made for every 
demand. We can do little more than note these facts : 
to attempt to reason upon the causes, why particular 
plants are endowed with peculiar faculties, would be 
mere idleness; yet, in remarking this, we cannot pass 
over the conviction, that the continual escape of mois- 
ture from one body, and its imbibition by another, this 
unremitting motion and circulation of matter, are parts 
