84 THE DOGSBANE. 



fluence of the weather; and it is the more remarka- 

 ble 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 sum- 

 mer 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 

 vigour certainly, but in a state of verdure beyond 

 any of its associates. The common burnet (pote- 

 rium sanguisorba) of our pastures, in a remarkable 

 degree, likewise possesses this faculty of preserving 

 its verdure, and flourishing amid surrounding ari- 

 dity and exhaustion. It is probable that these 

 plants, and some others, have the power of imbib- 

 ing that insensible moisture, which arises from the 

 earth even in the driest weather, or from the air 

 which passes over them. The immense evaporation 

 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 moisture from one body, 

 and its imbibition by another, this unremitting mo- 



