THE SOIL THE HOME OF THE PLANTS. 39 



inorganic materials than the soil immediately over it. 

 For instance, if any soil contains ninety per cent of 

 inorganic matter, and ten per cent of organic matter, 

 the subsoil under it may not have more than three per 

 cent of organic matter and ninety-seven per cent of 

 inorganic matter. The reason for this is plain. Plants 

 and animals that supply the organic materials live on 

 the surface of the ground. Rocks that by weathering 

 supply inorganic materials are below, and form the 

 foundation of all soils. Besides this, organic materials 

 are usually lighter than inorganic matter found in the 

 soil, and naturally the heavier material is beneath the 

 lighter material. There may be places, however, 

 where this is quite different ; as where a meadow, 

 having a soil that is almost wholly composed of the 

 remains of plants, may be covered with fine sands 

 swept over it by a flood from the hills. The two are, 

 however, in all cultivated soils, mixed together, and 

 often so completely mingled that it is very difficult 

 to separate them. Both organic and inorganic matters 

 are necessary to the existence of all plants growing in 

 a soil. 



On the Hartford and New-Haven Railroad, a few 

 miles north of New Haven, there is, on both sides of 

 the track for a mile or more, a level bit of country 

 where not a tree or shrub or blade of grass can be 

 seen. The ground is covered with loose yellow sand, 

 that in dry weather drifts hither and thither in the 

 wind. Before the road was ballasted with stone, it 

 was a terrible place to pass, on account of the dread- 



