1861 pages 15, 120; ‘Gardeners’ Chronicle’ 1869 page 389; ‘The Naturalist in Nicaragua’ page 129; ‘Journal of the Linnean Society Botany’ volume 13 1872 page 151.) I may add that I often saw in Chile a Mimus with its head yellow with pollen from, as I believe, a Cassia.  I have been assured that at the Cape of Good Hope, Strelitzia is fertilised by the Nectarinidae.  There can hardly be a doubt that many Australian flowers are fertilised by the many honey-sucking birds of that country.  Mr. Wallace remarks (address to the Biological Section, British Association 1876) that he has “often observed the beaks and faces of the brush-tongued lories of the Moluccas covered with pollen.”  In New Zealand, many specimens of the Anthornis melanura had their heads coloured with pollen from the flowers of an endemic species of Fuchsia (Potts ’Transactions of the New Zealand Institute’ volume 3 1870 page 72.) Next in importance, but in a quite subordinate degree, is the wind; and with some aquatic plants, according to Delpino, currents of water.  The simple fact of the necessity in many cases of extraneous aid for the transport of the pollen, and the many contrivances for this purpose, render it highly probable that some great benefit is thus gained; and this conclusion has now been firmly established by the proved superiority in growth, vigour, and fertility of plants of crossed parentage over those of self-fertilised parentage.  But we should always keep in mind that two somewhat opposed ends have to be gained; the first and more important one being the production of seeds by any means, and the second, cross-fertilisation.

The advantages derived from cross-fertilisation throw a flood of light on most of the chief characters of flowers.  We can thus understand their large size and bright colours, and in some cases the bright tints of the adjoining parts, such as the peduncles, bracteae, etc.  By this means they are rendered conspicuous to insects, on the same principle that almost every fruit which is devoured by birds presents a strong contrast in colour with the green foliage, in order that it may be seen, and its seeds freely disseminated.  With some flowers conspicuousness is gained at the expense even of the reproductive organs, as with the ray-florets of many Compositae, the exterior flowers of Hydrangea, and the terminal flowers of the Feather-hyacinth or Muscari.  There is also reason to believe, and this was the opinion of Sprengel, that flowers differ in colour in accordance with the kinds of insects which frequent them.

Not only do the bright colours of flowers serve to attract insects, but dark-coloured streaks and marks are often present, which Sprengel long ago maintained served as guides to the nectary.  These marks follow the veins in the petals, or lie between them.  They may occur on only one, or on all excepting one or more of the upper or lower petals; or they may form a dark ring round the tubular part of the corolla,