THE FERTILIZATION OF FLOWERS BY INSECTS, ETC. 681 
fertilize other flowers of the same species. This line of research, 
which had been almost lost sight of since Sprengel’s time, has 
been renewed in our own day by Darwin in this country, the writer 
of this volume and Hildebrand in Germany, Axell in Sweden, and 
Delpino in Italy; the first-named naturalist reducing the sum of 
his observations to the well-known aphorism that “nature abhors 
perpetual self-fertilization.” The whole of that complicated struc- 
ture which we call in ordinary language the “flower” of a plant 
consists, in fact, of the reproductive organs enclosed in a number 
of envelopes which have for their purpose not only the protection 
of the essential organs within them, but the attraction of those 
insects or other animals which are necessary for the fertilization 
of the ovules. 
The contrivances for effecting this purpose, though infinite in 
number and variety, may be classed under two principal heads, 
color and scent. A large number of insects obtain their food 
chiefly or entirely from the juices of flowers; and the necessity 
for cross-fertilization renders the visits of these insects as indis- 
pensable to the life of the flower as to that of the insect. o 
enable them to find this food the juices are very commonly scented ; 
a field of clover or beans will attract all the bees in the neighbor- 
hood from a great distance; and, if carefully watched, the bees 
will be found not only to carry off with them the honey, but to 
transfer also a portion of the pollen from flower to flower. Where 
the juice of the flower does not happen to be scented, the bright 
color of the corolla commonly serves the purpose of attracting 
insects from a distance. Different insects and other small animals 
have apparently very different ideas of beauty as regards the form 
and color of the flower. Hummingbirds are said by Delpino to 
have a penchant for scarlet and for flowers with long wide tubes ; 
hence in countries where there are no hummingbirds, as our own, 
scarlet flowers or those with long wide tubes are very rare among 
native plants.* The largest-flowered of European plants, the 
peony and several species of convolvulus, are visited chiefly by 
large beetles allied to the cockchafer; and as we proceed farther 
north to climates too cold for this description of insect, the corre- 
sponding flowers also disappear, not being able to mature their 
seeds without assistance. When fertilization is effected by very 
* Among our common wild flowers it would be difficult to name any of a true scar- 
let h: 1 3 eha littl . 3 ` 
