14 TROPICAL AGRICULTURE CHAP, n 



other mosses grow up on the dead ones, until, after numbers 

 of years, the humus fills up the hollows and forms what is 

 known as peaty land. 



fufFnsoils Stones are simply particles of the original rock from which 

 the soil was formed. They vary greatly in size and shape. 

 Some are rounded, others are sharp and irregular. If 

 they do not exist in too great a number they serve a useful 

 purpose in the soil, as they render the land lighter in 

 character, while they assist in retaining moisture in the soil, 

 and by their gradual wasting away slowly add material to 

 the earth. For the stones are weathered by the atmosphere 

 and other agencies in the same way as the rocks from which 

 the soil was made. 



