LECTUEE X 

 THE ORIGIN OF FLOWERS 



Introduction — Precursors of Darwin— Pollination by wind — Arrangements in 

 flowers for securing cross-fertilization— Salvia, Pedicularis— Flowers visited by flies— 

 Aristolochia— Pinguicula— Daphne— Orchids— Flowers are built up of adaptations— 

 Mouth-parts of insects— Proboscis of butterflies— Mouth-parts of the cockroach— Of the 

 bee— Pollen baskets of bees— Origin of flowers— Attraction of insects by colour- 

 Limitation of the area visited— Nageli's objection to the theory of selection— Other 

 interpretations excluded— Viola calcarata— Only those changes which are useful to their 

 possessors have persisted— Deceptive flowers— Cypripedium— Pollinia of Orchis— The 

 case of the Yucca-moth— The relative imperfection of the adaptations tells in favour of 

 their origin through natural selection — Honey thieves. 



When one species is so intimately bound up with another that 

 neither can live for any length of time except in partnership, that is 

 certainly an example of far-reaching mutual adaptation, but there 

 are innumerable cases of mutual adaptation, in which, although there 

 is no common life in the same place, yet the first form of life is 

 adjusted in relation to the peculiarities of the second, and the second 

 to those of the first. One of the most beautiful, and, in regard to 

 natural selection, the most instructive of these cases is illustrated by 

 the relations between insects and the higher plants, relations which 

 have grown out of the fact that many insects have formed the habit 

 of visiting the flowers of the plants for the sake of the pollen. In 

 this connexion the theory of selection has made the most unexpected 

 and highly interesting disclosures, for it has informed us how the 

 flowers have arisen. 



In earlier times the beauty, the splendour of colour, and the 

 fragrance of flowers were regarded as phenomena created for the 

 delight of mankind, or as an outcome of the infinite creative power 

 of Mother Nature, who loves to run riot in form and colour. Without 

 allowing our pleasure in all this manifold beauty to be spoilt, we 

 must nowadays form quite a different conception of the way in which 

 the flowers have been called into being. Although here, as every- 

 where else in Nature, we cannot go back to ultimate causes, yet we 

 can show, on very satisfactory evidence, that the flowers illustrate 

 the reaction of the plants to the visits of insects, and that they have 

 been in large measure evoked by these visits. There might, indeed, 



