420 The Biology of Flowers 
expression of the fact that cross-fertilisation is exceedingly wide- 
spread and has been shown in the majority of cases to be beneficial, 
and that in those plants in which we find self-pollination regularly 
occurring cross-pollination may occasionally take place. 
An attempt has been made to express in brief the main results 
of Darwin’s work on the biology of flowers. We have seen that his 
object was to elucidate important general questions, particularly the 
question of the significance of sexual reproduction. 
It remains to consider what influence his work has had on 
botanical science. That this influence has been very considerable, 
is shown by a glance at the literature on the biology of flowers 
published since Darwin wrote. Before the book on orchids was 
published there was nothing but the old and almost forgotten works 
of Kélreuter and Sprengel with the exception of a few scattered 
references. Darwin’s investigations gave the first stimulus to the 
development of an extensive literature on floral biology. In Knuth’s 
Handbuch der Blitenbiologie (Handbook of Flower Pollination, 
Oxford, 1906) as many as 3792 papers on this subject are enumerated 
as having been published before January 1, 1904. These describe not 
only the different mechanisms of flowers, but deal also with a series of 
remarkable adaptations in the pollinating insects. As a fertilising rain 
quickly calls into existence the most varied assortment of plants on a 
barren steppe, so activity now reigns ina field which men formerly left 
deserted. This development of the biology of flowers is of importance 
not only on theoretical grounds but also from a practical point of view. 
The rational breeding of plants is possible only if the flower-biology of 
the plants in question (i.e. the question of the possibility of self- 
pollination, self-sterility, etc.) is accurately known. And it is also 
essential for plant-breeders that they should have “the power of 
fixing each fleeting variety of colour, if they will fertilise the flowers 
of the desired kind with their own pollen for half-a-dozen genera- 
tions, and grow the seedlings under the same conditions+.” 
But the influence of Darwin on floral biology was not confined 
to the development of this branch of Botany. Darwin’s activity in 
this domain has brought about (as Asa Gray correctly pointed out) 
the revival of teleology in Botany and Zoology. Attempts were 
now made to determine, not only in the case of flowers but also in 
vegetative organs, in what relation the form and function of organs 
stand to one another and to what extent their morphological 
characters exhibit adaptation to environment. A branch of Botany, 
which has since been called Ecology (not a very happy term) has 
been stimulated to vigorous growth by floral biology. 
1 Cross_and Self fertilisation (1st edit.), p. 460. 
