pollen of another plant, to the abiding gain all round of the plant, whose blood, as we may say, is thus mixed with that of a stranger. Two agencies--insects and the wind--undesignedly effect this; while in the dispersion of the matured seed, birds and other animals play an important, although equally unconscious, part. Plants which are wind-fertilized have no gayly colored petals or sepals, and do not secrete water. Such are the naked-seeded groups whose sombre flowers are borne on dull brown cones; and, among cover-seeded groups, grasses and rushes, with their feathery flowers; and willows and birches, with their long waving clusters of catkins. All of these provide against the fitfulness of the wind, which is as likely to blow the pollen one way as another, by producing it in large quantities. Plants which are insect-fertilized seek to attract their visitors by secreting honey and developing colored floral organs. The way in which this came about is probably as follows: The common idea about flowers is that they are made up of petals and sepals, whereas the _essential_ parts are the stamens and pistils--_i. e._, the male, or pollen-producing organs, and the female, or seed-containing organs. The earliest flowers consisted of these alone, having no colored whorl of petals within another colored whorl of sepals, but were only scantily protected by leaves, as are many extant species. These the food-seeking insects then, as now, visited for the sake of the pollen, to the detriment of the plant, which lost the fertilizing stuff and gained nothing in return. To arrest this, certain plants began, especially when in the act of flowering, to secrete honey and store it in glands or nectaries, or near their seed-vessels, where the insects could not get at it without covering their bodies with some of the pollen, which they rubbed on the pistils of the plant next visited, and thus fertilized the ovule, provided that the plants were nearly related. Honey is sweeter to the taste than pollen, and the plants that produced the most honey stood the better chance of visits from insects, and therefore of fertilization, to the advantage of this species over others. As a rule, those which secrete honey have hairy coverings at the base of the petals, or other contrivances to prevent it being washed out by the rain or dew, or seized by useless insects, and we find curious interrelations established between plants and their desired visitors. Certain flowers adapt themselves to certain insects, and _vice versâ_, as where the plant has secreted the honey at the bottom of a long tube and the insect has developed a correspondingly long proboscis to gather it. By these and kindred devices the pollen is preserved for its sole function, the energy of the plant being conserved in the smaller quantity which it has to produce. As the honey was secreted as counter-attraction to the pollen, so the colored floral envelopes were developed to attract