Never retain the same kinds of seeds too long upon the land; at the end of three years it will generally deteriorate, and ought to be changed; change of seed always produces a change for the better in the crops. Heavy clay-lands will longest retain the seed pure; light loams and peat soils will sooner require the change. In selecting seed it should be Ascertained, if possible, where, and on what kind of soil it grew; and select a soil of different quality to that on which it is to be sown. Never select 6eed from a rich soil to sow it on a poor; but prefer that from a poor soil to sow it on a rich. Always select seed well cleaned and pure, being strictly of the same kind; seeds of different kinds will vegetate at different times, and ripen at different seasons, which occasions serious loss and further deterioration of sample.