s to go quickly and directly to the opening
of the flower, and is equally important in aiding them to obtain a
better supply of food, and to fertilise a larger number of flowers.

8. Flowers have been specially adapted to the kinds of 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, important to have a modification of structure which
shall make butterflies the fertilisers, and this in many cases has been
done.[148]

9. Economy of time is very important both to the insects and the
flowers, because the fine working days are comparatively few, and if no
time is wasted the bees will get more honey, and in doing so will
fertilise more flowers. Now, 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 distinct 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 Galeobdolon),
all distinct and well-contrasted flowers. In damp meadows in summer we
have the