In the cultivation of grass the farmer will find it to his advantage to cultivate none but the best kinds; the whole pasture lands will then be filled with valuable grass seeds. The number of grass seeds worth cultivating is but few, and these should be sown separately. It is bad policy to sow different kinds of grass seed together--just as bad as to sow wheat, oats, turnips, and corn promiscuously. The reason why the farmers, as a community, will be benefited by sowing none but the best seed is, because grass seeds are distributed through neighboring pastures by the winds, and there take root. Now, if the neighboring pastures abound in inferior grasses, the fields will soon be filled with useless plants, which are very difficult to be got rid of. We refer those of our readers who desire to make themselves acquainted with animal chemistry to Professor Liebig's work on that science. ON BREEDING. Large sums of money have, from time to time, been expended with a view of improving stock, and many superior cattle have been introduced into this country; yet, after a few generations, the beautiful form and superior qualities of the originals are nearly lost, and the importer finds to his cost that the produce is no better than that of his neighbors. What are the causes of this deterioration? We are told--and experience confirms the fact--that "like produces like." Good qualities and perfect organization are perpetuated by a union of animals possessing those properties: of course it follows, that malformation, hereditary taints, and vices are transmitted and aggravated. The destructive practice of breeding "in and in," or, in other words, selecting animals of the same family, is one of the first causes of degeneracy; and this destructive practice has proved equally unfortunate in the human family. Physical defects are the result of the intermarriage of near relatives. In Spain, the deformed and feeble state of the aristocracy arises from their alliances being confined to the same class of relatives through successive generations. But we need not go to Spain to verify such facts. Go into our churchyards, and read on the tombstones the names of thousands of infants,--gems withered in the bud,--young men, and maidens, cut down and consigned to a premature grave; and then prove, if you can, that early marriages and near alliances are not the chief causes of this great mortality.