318 DARWINISM chap. 



insects that most abound where they grow. Thus the gentians 



of the lowlands are adapted to bees, those of the high alps to 

 butterflies only; and while most species of Rhinanthus (a 

 genus to which our common "yellow rattle" belongs) are bee- 

 flowers, one high alpine species (R. alpinus) has been also 

 adapted for fertilisation by butterflies only. The reason of 

 this is, that in the high alps butterflies are immensely more 

 plentiful than bees, and flowers adapted to be fertilised by 

 bees can often have their nectar extracted by butterflies 

 without effecting cross -fertilisation. It is, therefore, im- 

 portant to have a modification of structure which shall make 

 butterflies the fertilisers, and this in many cases has been done. 1 



9. Economy of time is very important both to the insects 

 and the flowers, because the fine working days are com- 

 paratively few, and if no time is wasted the bees will get 

 more honey, and in doing so will fertilise more flowers. Xow, 

 it has been ascertained by several observers that many insects, 

 bees especially, keep to one kind of flower at a time, visiting 

 hundreds of blossoms in succession, and passing over other 

 species that may be mixed with them. They thus acquire 

 quickness in going at once to the nectar, and the change of 

 colour in the flower, or incipient withering when fertilised, 

 enables them to avoid those flowers that have already had 

 their honey exhausted. It is probably to assist the insects in 

 keeping to one flower at a time, which is of vital importance 

 to the perpetuation of the species, that the flowers which 

 bloom intermingled at the same season are usually very dis- 

 tinct both in form and colour. In the sandy districts of 

 Surrey, in the early spring, the copses are gay with three 

 flowers — the primrose, the wood-anemone, and the lesser 

 celandine, forming a beautiful contrast, while at the same 

 time the purple and the white dead-nettles abound on hedge 

 banks. A little later, in the same copses, we have the blue 

 wild hyacinth (Scilla nutans), the red campion (Lychnis 

 dioica), the pure white great starwort (Stellaria Holosteum), 

 and the yellow dead-nettle (Lamium C4aleobdolon), all distinct 

 and well-contrasted flowers. In damp meadows in summer 

 we have the ragged robin (Lychnis Floscuculi), the spotted 

 orchis (0. macnlata), and the yellow rattle (Rhinanthus 



1 "Alpenblumen," by D. H. Miiller. See Nature, vol. xxiii. p. 333. 



