332 
DARWINISM 
CHAP. 
and organ, with the enormous powers of increase possessed by 
plants, have enabled them to become again and again readjusted 
to each change of condition as it occurred, resulting in that 
endless variety, that marvellous complexity, and that ex¬ 
quisite colouring which excite our admiration in the realm of 
flowers, and constitute them the perennial charm and crowning 
glory of nature. 
Flowers the Product of Insect A gency. 
In his Origin' of Species , Mr. Darwin first stated that 
flowers had been rendered conspicuous and beautiful in order 
to attract insects, adding : “ Hence we may conclude that, if 
insects had not been developed on the earth, our plants would 
not have been decked with beautiful flowers, but would have 
produced only such poor flowers as we see on our fir, oak, nut, 
and ash trees, on grasses, docks, and nettles, which are all 
fertilised through the agency of the wind.” The argument in 
favour of this view is now much stronger than when he wrote ; 
for not only have we reason to believe that most of these 
wind-fertilised flowers are degraded forms of flowers which 
have once been insect fertilised, but we have abundant evidence 
that whenever insect agency becomes comparatively ineffective, 
the colours of the flowers become less bright, their size and 
beauty diminish, till they are reduced to such small, greenish, 
inconspicuous flowers as those of the rupture-wort (Herniaria 
glabra), the knotgrass (Polygonum aviculare), or the cleisto- 
gamic flowers of the violet. There is good reason to believe, 
therefore, not only that flowers have been developed in order 
to attract insects to aid in their fertilisation, but that, having 
been once produced, in however great profusion, if the insect 
races were all to become extinct, flowers (in the temperate 
zones at all events) would soon dwindle away, and that 
ultimately all floral beauty would vanish from the earth. 
We cannot, therefore, deny the vast change which insects 
have produced upon the earth’s surface, and which has been 
thus forcibly and beautifully delineated by Mr. Grant Allen : 
“ While man has only tilled a few level plains, a few great river 
valleys, a few peninsular mountain slopes, leaving the vast mass 
of earth untouched by his hand, the insect has spread himself 
over every land in a thousand shapes, and has made the whole 
