PLATE X. Fig. 1. _Nectarinea chloropygia._ _p._ 90. Fig. 2. _Nectarinea christinæ._ These birds illustrate regional colouration well. LEAVES. PLATE XI. Fig. 1. Horse Chestnut, _Æschulus hippocastanum_, decaying. _p._ 95. Fig. 2. _Coleus._ Fig. 3. _Begonia rex._ Fig. 4. _Begonia_. Fig. 5. _Caladium bicolor._ Fig. 6. _Anoechtochilus xanthophyllus._ FLOWERS. PLATE XII. Fig. 1. _Gloxinia_, with 5 petals, showing uneven _p._ 96. colouring. Fig. 2. _Gloxinia_, with 6 petals, showing regular colouring. Figs. 3 and 4. Pelargoniums, showing the variation of the dark markings with the different sized petals. [Illustration] COLOURATION IN ANIMALS AND PLANTS. CHAPTER I. INTRODUCTION. Before Darwin published his remarkable and memorable work on the Origin of Species, the decoration of animals and plants was a mystery as much hidden to the majority as the beauty of the rainbow ere Newton analysed the light. That the world teemed with beauty in form and colour was all we knew; and the only guess that could be made as to its uses was the vague and unsatisfactory suggestion that it was appointed for the delight of man. Why, if such was the case, so many flowers were "born to blush unseen," so many insects hidden in untrodden forests, so many bright-robed creatures buried in the depths of the sea, no man could tell. It seemed but a poor display of creative intelligence to lavish for thousands of years upon heedless savage eyes such glories as are displayed by the forests of Brazil; and the mind recoiled from the suggestion that such could ever have been the prime intention. But with the dawn of the new scientific faith, light began to shine upon these and kindred questions; nature ceased to appear a mass of useless, unconnected facts, and ornamentation appeared in its true guise as of extreme importance to the beings possessing it. It was the theory of descent with modification that threw this light upon nature.