Turning now to the plants which are used by man, it may be pointed out in the first place that the human race obtains much more, whether of profit or of pleasure, from the vegetable than from the animal kingdom. Flesh, whether derived from mammals, birds, or fishes; wool, silk, leather, oils, and so on, bulk much less than the grains, vegetables, fruits, timber, fibres, fodder plants, and other vegetable products which we use in our daily life. On the æsthetic side, again, while the beauty of birds and insects is a source of frequent delight, flowers play a part in daily life that the more delicate and sensitive animals can never do. Again, in the number of different species used, whether for profit or pleasure, the plant world takes precedence. This is especially the case as regards our farms and pleasure grounds, plants lending themselves much more readily to domestication than animals do. And so a suburban house may have a hundred or a thousand different plants in kitchen garden and flower plot, orchard, and shrubbery, while its animal dependents consist of a horse, a couple of dogs, a cat, some fowl, and a canary. So again a Botanic Garden may easily possess as many thousands of different species as a Zoological Garden contains hundreds. This army of plants which human beings collect about themselves may be grouped under two categories--useful and ornamental. On a previous page (p. 136) a suggestion has been made as to how the cultivation of useful plants may have arisen. As now practised, this industry is the largest in the world, and with the growth of means of transport has ceased to be only or even mainly of local importance: we use every day wheat from Australia, rice from China, tea from India, cotton from the United States, timber from Norway. In some cases, as in the last, these materials are harvested as they occur in the wild state, but in the majority of instances the plants are not merely conserved, but cultivated; cultivation has led to selection of the best varieties; and continued selection has resulted in the production of forms often very different in appearance from the wild plants from which they originated. We cannot _create_ new forms; but by taking advantage of the innate tendency to vary which all plants display--some to a much greater degree than others--and by raising, generation after generation, the seeds of those individuals in which a certain abnormal feature is best displayed, we can produce an artificial race in which the selected character may be developed to an extraordinary degree. But we have not by this means produced a new species. Seedlings of such plants will tend to “throw back” towards the original form; we can preserve or improve the special characters only by continued selection; if allowed to grow and seed unchecked, most of such plants will revert to the natural type in a few generations. Often this reversion is so rapid that seeds are useless for