298 THE SUCCESSIVE OAKS. 



though there are some trees that grow in the salt 

 water, and actually invade the ocean. The man- 

 groves that abound so much on the muddy shores 

 of tropical countries, and form a sort of soil like the 

 Ultima Thule of the ancients, neither land nor sea, 

 are a remarkable instance of that, and the maritime 

 pines of the Mediterranean shores are another. 

 Metallic fumes are very hurtful to vegetation, more 

 especially those that contain lead; and the trees 

 near lead mines are few and sickly. Saline efflo- 

 rescences upon the surface of the ground destroy 

 vegetation ; and works where sulphur is burnt into 

 sulphuric acid, and those at which Prussian blue, 

 and various other colouring matters are prepared, 

 are, if possible, more so. 



Now it is evident, whatever substance has an inju- 

 rious effect upon trees in an advanced stage of their 

 growth must be much more injurious to them at the 

 very commencement. But the commercial advan- 

 tages of having nurseries for forest trees, as well as 

 other plants, near great towns, are so many, and so 

 much more obvious than the injuries that may thus 

 be done to the trees, that many of them are in very 

 tainted atmospheres. Ground there is high rented, 

 and the plants are in consequence huddled together 

 as closely as possible, both in the seed beds, and after 

 they are transplanted. Still, with the rich soil and 

 skilful management in such places, the trees rush 

 up quickly and look well, so that they are more 

 " taking to the eye," and fetch higher prices, than 

 if they were to produce better timber. Indeed, those 

 plants, inferior as their timber must be, are actually 

 the most acceptable to the immediate planter. Most 

 species of forest trees are so long in coming to ma- 

 turity, that the grand incentive to the planting of 

 them is ornament, and not use. Even the man who 

 accumulates for posterity, in reality seldom does so 

 in his own feeling of the matter ; for he who leaves 

 the most to others when he quits the world, did not 



