Page:Popular Science Monthly Volume 37.djvu/391

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feral plants. In other words, the cultivated plant is living an unnatural existence; stimulated by man's careful attention and guided by his will, it yields to the demands of its guardian. Variations quickly arise under such fostering conditions, and such changes as are advantageous to man are, if possible, perpetuated by him. This perpetuity in many instances can only be accomplished by non-sexual methods, as by cuttings, graftings, etc., and it therefore follows that the seeding process is either ignored or prevailed against. With their energies all turned in some other channel, plants may in time cease to develop seed.

A flower of the showy sort we may consider as the product of two great forces or groups of forces—namely, that which is within the plant, and for the lack of a better term may be called the constructive ability of the plant; and those forces which act from without, and are included in the general term environment The chief factor in this last or external force is the modifying influence of insects, due primarily to irritation. For example, the lily-flower in its wild state has reached its present condition because the mother plants and their insect attendants have worked together to produce a structure that is admirably adapted to the needs of each. It is, it seems to me, not asking too much of any one who is a disciple of evolution, even in its mildest form, to conceive that the simplest wind-fertilized flowers were the first of all floral structures to appear in the far-away geologic times. In those early ages, provided that we base our reasoning upon what is seen to-day, it is easy to understand that out of the foliar structures there were evolved the primitive ovary and the ante-Adamite stamen. That ancient ovary might stand in striking contrast with the simple pistil of a pine-cone or leaf serration of a cycas, and the corresponding stamen was perhaps only a slight modification of a common leaf. But out of these primitive essential organs came, by slow but by an ever-advancing adaptation to the surrounding world, the wonderful combinations of color, odor, and form which we see in the more complex floral structures of the present day.

All the conspicuous parts of the flower outside of the essential organs are for the purpose of securing a transfer of pollen from the stamen of one flower to the pistil of another. This process of cross-fertilization, as has been abundantly shown, is an advantage to the offspring, which are stronger and therefore better able to cope with surrounding rivals. Therefore, any change in floral structure, however slight, born of accident as some would say, or the result of an inward impulse to improve, is one step toward that ideal condition of perfect adaptation between a plant and its surroundings. So far as the sexual elements are concerned, this ideal adjustment seems to be that of wide separation, and accord-