BOTANY FOR YOUNG PEOPLE. 131 



climate, or locality to which that structure is 

 fitted. 



The Heath that grows on the stormy -Cape of 

 Good Hope, has as much elastic power in its 

 stem as if it were made of spring steel, and so 

 energetic are the vital powers of the plants in 

 general of that place, that Thunberg, having 

 carefully taken one up and laid it on a stone, 

 found it after three years in vigorous health and 

 vegetating, having gained some inches, deriving 

 its aliment alone from the moisture and coolness 

 of the stone. 



L. If every thing in nature is wisely provided, 

 and has its uses, I should like to know of what 

 possible benefit to man are poisonous plants ? 



E. They may be of great benefit to him in- 

 directly, by feeding the animals, as I formerly 

 mentioned, which he eats ; you must remember 

 that what are poisonous to him are not so in all 

 cases, to other animals. 



But more than this, some writers ascribe to 

 them another very important use, that of puri- 

 fying the atmosphere from unhealthy miasms. 

 We find the greatest number of those plants 

 always in unheathy natural situations, as on 

 the borders of marshes ; and as they abound 



