solubly associated with the perpetuation of every kind of highly-organised plant. The necessary structures of a flower, stamens and pistil, have already been described (Chap. III.), and we there saw that the rest of floral organs are auxiliaries, although to people unacquainted with botanical details a flower has no charm without brightly-coloured and attractive petals; and horticulturists do their best to convert the true floral organs, stamens and pistils alike, into petals-whence the origin of the double flowers seen in all gardens. Mr. Herbert Spencer long ago pointed out that the act of flowering must of necessity take place where the energy conducive to growth is balanced by the forces which resist growth. At this balanced point germs can be produced and easily thrown off, because nutrition to the individual plant must there be failing. Hence flowers are generally borne at the terminal ends or shoots of branches, where nourishment is least, and not most abundantly supplied. It may seem to many people very strange to regard flowers as lower in organisation than leaves; but we have seen such is the case from a structural point of view. Floral organs are in reality aborted leaves, although, since flowers came into existence, and have had to adapt themselves to their organic and inorganic surroundings, they have done the best they could with them, and even converted and modified their auxiliary and other floral organs, until they are now the chief marvels of vegetable organisation, and the delight of every cultivated mind. To thoroughly understand the amazing varietyin size, shape, colour, and perfume-among flowers we must consider the whole question from their own point of view. Hitherto we have taken it for granted that flowers were created chiefly, if not wholly, for human delight or use, and have, with an unintentional irreligion due to ignorance, expressed our wonder why all plants did not administer either to our utilitarian or æsthetic needs! It is not necessary here to mention the ingenious guesses which have been put forth to account for the apparent anomaly of unattractive, useless, and even poisonous plants; for no botanist now doubts that such speculations are all wrong. If modern botany had done nothing besides abolishing these crude views, it would have a claim to gratitude; but it has done more-it has taught us to regard plants as fellow creatures, regulated by the same laws of life as those affecting human beings themselves! To understand the structure of flowers, therefore, we must first of all consider how far they are useful to the end for which flowers were developed. This, of course, is the production of seeds, each of which contains an embryonic individual plant. The process by which an ovule is converted and developed into a seed has already been sketched. Such process is called "Fertilisation." No fact in modern botany has been better proved than that "crossing" is beneficial-in other words, that the seeds of flowers whose pistils have been fertilised by the pollen brought from the stamens of another flower, and especially from that of another plant, produce better and stronger individuals than the seeds would have ripened into if the pistils had been fertilised by pollen from the stamens of the same flower. The strongest efforts of the floral world are put forth with the view to flowers being "crossed." In every country, in every geological period since flowers were first differentiated, the competition has been going on. It is now in the midst of its fiercest and intensest action, for never before, in the entire history of our planet, were the agencies involved in it so complex. Here the race is to the swift, and the battle to the strong. Those best handicapped s in the race win-the hindmost linger on as best they can. The botanist recognises self-fertilisation or only occasional crossing, in the weakly, dwarfed, small-flowered species, most of which are best known by the popular name of "weeds," a term expressive of their uselessness and usual lack of floral beauty and strength. Between such individuals and the most complex of floral mechanisms we find every possible stage of organisation. It is because of this gradation that flowers have such marvellous diversity. The desirability of being "crossed," because of the greater certainty that more and stronger seeds will be the result, from which may possibly spring a succeeding generation of plants even more robust than their ancestors, is as important an element in the life of an individual plant as it is for man to work and save, so that his children may be better placed in society. But if all plants adopted the same contrivances to be crossed, there would be a painful floral monotony. Some flowers might then be large and others small, but there would be nothing of the amazing varieties of floral shapes, colours, and perfumes, we see everywhere around us. No person possessed of even the most rudimentary knowledge of flowers can help grouping them under two kinds-attractive and non-attractive. It has just been mentioned that many of the latter are so because they are self-fertilised. But this latter class is slenderly represented, so that we may leave it out of our calculation just now. Observe the number of plants, shrubs, and trees, which bear flowers so thoroughly deprived of all the organs and qualities with which we associate them, that many people express surprise when they hear they bear flowers at all. Among our British plants such species as the Dog's Mercury, the Nettles, Wild Hop, Pellitory, Hazel, Birch, Poplar, Alder, Oak, etc., as well as an immense number of species of grasses, sedges, |