This series Of agricultural texts is based on the theory that the successful farmer should know the physical and biological forces with which he has to contend; that he should understand the laws under which these forces Operate; and that he should acquire some skill in directing them. He should ultimately become able to adjust and correlate these forces so as to bring them all under the orderly operation of economic law. In con formity with the above theory this series has been made to cover the following fundamental divisions'