cultural purposes, and it is only by cuttings or graftings--that is, by growing parts of the original possessor of the required characters--that constancy can be maintained; this is what is usually done in the case of fruit-trees, Roses, Pansies, and so on. Equally efficient in the hands of the cultivator has been another method of producing new forms--namely, hybridization. If the pollen of a plant be transferred to the stigma of a related species, offspring is often produced; and the product is a batch of plants intermediate in characters between the two parents, and generally uniform in appearance. Should these be crossed again, a heterogeneous offspring is the result, displaying a variety of characters inherited from one or other original parent. The crossing of varieties, native or cultivated, has the same result. Hybrids occur in nature, but not very frequently. Insects visiting flowers are well known to confine their attention to a great extent to one species at a time, so as agents of hybridization they are not efficient. Again, many hybrids do not produce fertile seed, so that if they arise by natural means they are not perpetuated. In the garden, hybridizing has been resorted to largely; but its practice is not so ancient as the method of producing improved breeds by selection. The cultivation of specially selected forms is certainly of remote origin, and probably goes back to the earliest days of agriculture: of early date, too, is the introduction into regions where they do not occur naturally of plants desirable for their use or beauty. The records of the cultivation of the Vine, for instance, go back for five or six thousand years in Egypt. Two thousand years ago Pliny writes that ninety-one principal forms could be reckoned in his day, though “the varieties are very nearly as numberless as the districts in which they grow.” Theophrastus, three hundred years earlier, discourses learnedly of the different kinds of cultivated Figs, etc., and their superiority over the wild kinds. These and other authors make frequent mention of plants introduced into Greece or Italy from the East for their usefulness or their pleasing qualities. Nowadays, the number of species cultivated, the innumerable forms of these which are grown, and the wide distribution which these forms have attained, have resulted in the cultivated flora of a country like England being, so far as the higher plants are concerned, much larger than the native flora, even when all the plants which are grown under glass are left out of consideration.