for cereals, then it is sheer folly to sow any more corn than may be needful for convenience, as, for example, to supply straw for thatching and litter, and oats for horses, to save cost of carriage, &c.  On large farms that are far removed from markets it is often necessary to risk a few crops that the land is ill fitted for, in order to satisfy the requirements of the homestead, and to save the outlay of money and the inconvenience of hauling from distant markets.  But everywhere the cropping must be adapted to the soil and the climate as nearly as possible, both to simplify operations and enlarge to the utmost the chances of success.  In the cropping of a garden this plain procedure cannot be followed.  We are compelled certainly to consider what the soil and climate will especially favour amongst garden crops, but, notwithstanding this, the gardener must grow whatever the household requires.  He may have to grow Peas on a hot shallow sand; and Potatoes and Carrots on a cold clay; and Asparagus on a shallow bed of pebbles and potsherds.  To the gardener the chemistry of crops is a matter of great importance, because he cannot restrict his operations to such crops as the land is particularly adapted for, but must endeavour to make the land capable of carrying more or less of all the vegetables and fruits that find a place in the catalogue of domestic wants.  That he must fail at certain points is inevitable; nevertheless his aim will be, and must be, of a somewhat universal kind, and a clear idea of the relations of plants to the soil in which they grow will be of constant and incalculable value to him.

We are bound to say at the outset that a complete essay on the chemistry of vegetation is not our purpose.  We are anxious to convey some useful information, and to kindle sufficient interest to induce those who have hitherto given but slight attention to this question to inquire further, with a view to get far beyond the point at which we shall have to quit the subject.

Plants consist of two classes of constituents—­the Inorganic, which may be called the foundation; and the Organic, which may be considered the superstructure.  With the former of these we are principally concerned here.  A plant must derive from the soil certain proportions of silica, lime, sulphur, phosphates, alkalies, and other mineral constituents, or it cannot exist at all; but, given these, the manufacture of fibre, starch, gum, sugar, and other organic products depends on the action of light, heat, atmospheric air, and moisture, for the organic products have to be created by chemical (or vital) action within the structure, or, as we sometimes say, the tissues of the plant itself.  To a very great extent the agencies that conduce to the elaboration of organic products are beyond our control (though not entirely so), whereas we can directly, and to a considerable degree, provide the plant with the minerals it more particularly requires; first, by choosing the ground