330 DARWINISM chap. 



tubular flowers' increasing in length and irregularity, till in 

 some, like our common honeysuckle, they are adapted for 

 fertilisation by moths only, with abundant honey and 

 delicious perfume to attract them. In the Scrophulariaceae 

 we find open, almost regular flowers, as Veronica and 

 Verbascum, fertilised by flies and bees, but also self-fertilised ; 

 Scrophularia adapted in form and colour to be fertilised by 

 wasps ; and the more complex and irregular flowers of 

 Linaria, Rhinanthus, Melampyrum, Pedicularis, etc., mostly 

 adapted to be fertilised by bees. 



In the genera Geranium, Polygonum, Veronica, and several 

 others there is a gradation of forms from large and bright 

 to small and obscure coloured flowers, and in every case the 

 former are adapted for insect fertilisation, often exclusively, 

 while in the latter self-fertilisation constantly occurs. In the 

 yellow rattle (Rhinanthus Crista-galli) there are two forms 

 (which have been named major and minor), the larger and 

 more conspicuous adapted to insect fertilisation only, the 

 smaller capable of self-fertilisation ; and two similar forms exist 

 in the eyebright (Euphrasia officinalis). In both these cases 

 there are special modifications in the length and curvature 

 of the style as well as in the size and shape of the corolla ; 

 and the two forms are evidently becoming each adapted to 

 special conditions, since in some districts the one, in other 

 districts the other is most abundant. 1 



These examples show us that the kind of change suggested 

 above is actually going on, and has presumably always been 

 going on in nature throughout the long geological epochs 

 during which the development of flowers has been progressing. 

 The two great modes of gaining increased vigour and fertility 

 — intercrossing and dispersal over wider areas — have been 

 resorted to again and again, under the pressure of a constant 

 struggle for existence and the need for adaptation to ever- 

 changing conditions. During all the modifications that ensued, 

 useless parts were reduced or suppressed, owing to the absence 

 of selection and the principle of economy of growth ; and thus 

 at each fresh adaptation some rudiments of old structures were 



1 Miiller's Fertilisation of Flowers, pp. 448, 455. Other cases of recent 

 degradation and readaptation to insect - fertilisation are given by Professor 

 Henslow (see footnote, p. 324). 



