302 THE FLORIST AND 



the birch. The same takes place naturally. On the shores of the Rhine 

 are seen ancient forests of oak from two to four centuries old, gradually 

 giving place at present to a natural growth of beech, and others where the 

 pine is succeeding to both. In the Palatinate, the ancient oak-woods are 

 followed by natural pines ; and in the Jura, the Tyrol, and Bohemia, the 

 pine alternates with the beech. 



These and other similar differences are believed to depend in great part 

 upon the chemical composition of the soil. The slug may live well upon, 

 and therefore infest, a field almost deficient in lime ; the common land snail 

 will abound at the roots of the hedges only where lime is plentiful, and can 

 easily be obtained for the construction of its shells. So it is with plants. 

 Each grows spontaneously where its wants can be most fully and most easily 

 supplied. If they cannot move from place to place like the living animal, 

 yet their seeds can lie dormant, until either the hand of man or the opera- 

 tion of natural causes produces such a change in their position, in reference 

 to light, heat, &c, as to give them an opportunity of growing — or in the 

 composition and physical qualities of the soil itself, as to fit it for ministering 

 to their most important wants. 



And such changes do naturally come over the soil. The oak, after 

 thriving for long generations on a particular spot, gradually sickens ; its 

 entire race dies out, and other races succeed it. Has the operation of na- 

 tural causes gradually removed from the soil that which favored the oak, 

 and introduced or given the predominance to those substances which favor 

 the beech or the pine ? On the light soils of the state of New Jersey the 

 peach tree used to thrive better than anything else, and large sums of 

 money were made from the peach grounds in that state. But of later years 

 they have almost entirely failed. In Scotland, the Scotch fir has been 

 known at once to die out over an area of 500 or 600 acres — and the 

 forests of larch are now in many localities exhibiting a similar decay. This 

 decay is often, I believe, owing to the presence of noxious matters in sub- 

 soil, but it is due in some cases, also to a natural change in the composition 

 and character of the several soils, which has taken place since the peach, 

 the fir, and the larch trees were first planted upon them. 



In the hands of the farmer, the land grows sick of this crop — it becomes 

 tired of that. These facts may be regarded as indications of a change in 

 the chemical composition of the soil. This alteration may proceed slowly 

 and for many years ; and the same crops may still grow upon it for a suc- 

 cession of rotations. But at length the change is too great for the plant to 



