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 Kolreuter 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 Bliitenbiologie (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 in a 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 1 ." 



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. 



