318 SUCCESSION 



they did. The young of no tribe, vegetable or 

 animal, are the destroyers of the old ; they merely 

 come on, in succession, when they are required ; 

 and though the germs of all are exceedingly nu- 

 merous, so that there never is room on a fit soil 

 at the proper season, without the plant appearing 

 to fill it. But man comes in with his nursery- 

 bed ; and though he cannot be said to overstock 

 the country (for there can hardly be too many 

 trees and there are numerous and wide wastes 

 in England, where it is disgraceful that there are 

 not millions); yet the nursery-bed is overstocked, 

 and the consequence is, the dry rot in oak, and 

 general rottenness and want of strength in all 

 timber. 



The inferiority of planted timber is often at- 

 tributed to the act of transplanting ; but though 

 that may have a considerable influence upon the 

 growth, it cannot have so much on the quality of 

 the timber. Trees that have long top-roots, as 

 the oak has, cannot be transplanted without in- 

 juring them, and injuring them often to a con- 

 siderable extent ; but still that is only a mechani- 

 cal injury, and can affect only the size and ap- 

 pearance of the trees. 



The economy of vegetables has not been care- 

 fully and extensively enough examined, for en- 

 abling us to say what effects variously tainted 

 atmospheres have upon forest trees, or even upon 

 vegetables of any description; but enough is 

 known to let us see that they must be very per- 

 nicious. The air of the sea is very hurtful to all 

 plants that contain potass, though there are some 

 trees that grow in the salt water, and actually 

 invade the ocean. The mangroves that abound 



