VI DIFFICULTIES AND OBJECTIONS 133 



and colours of the flowers, the shapes and arrangement of the 

 leaves, and the numerous other external characters of the 

 whole plant. But since Mr. Dar^nn shoAved that plants 

 gained both in vigour and in fertility by being crossed Avith 

 other individuals of the same species, and that this crossing 

 was usually effected by insects which, in search of nectar or 

 pollen, carried the pollen from one plant to the flowers of 

 another plant, almost every detail is found to have a purpose 

 and a use. The shape, the size, and the colour of the petals, 

 even the streaks and spots Avith Avhich they are adorned, the 

 jjosition in AA'hich they stand, the moA^ements of the stamens 

 and pistil at A'arious times, es])ecially at the period of, and 

 just after, fertilisation, have been proved to be strictly 

 adaptiA^e in so many cases that botanists noAV belie\"e that all 

 the external characters of floAvers either are or have been of 

 use to the species. 



It has also been shoAAii, by Kerner and other botanists, 

 that another set of characteristics liaA'e relation to the pre- 

 A'ention of ants, slugs, and other animals from reaching the 

 floAA^ers, because these creatures Avould devoiu' or injure 

 them Avithout effecting fertilisation. The spines, hairs, 

 or sticky glands on the stem or floAver-stalk, the curious 

 hairs or processes shutting up the flower, or sometimes 

 even the extreme smoothness and polish of the outside of 

 the petals so that iew insects can hang to the part, have 

 been shoAvn to be related to the possible intrusion of 

 these "unbidden guests."^ And, still more recently, attempts 

 have been made by Grant Allen and Sir John Lubbock 

 to account for the innumerable forms, textures, and groupings 

 of leaves, by their relation to the needs of the plants 

 themselves ; and there can be little doubt that these 

 attempts ^^n\\ be ultimately successful. Again, just as floAvers 

 have been adapted to secure fertilisation or cross-fertilisation, 

 fruits have been developed to assist in the dispersal of seeds ; 

 and their forms, sizes, juices, and colours can be shoAvn to be 

 specially adapted to secure such dispersal by the agency of 

 birds and mammals ; Avhile the same end is secured in other 



^ See Kenier's Floivers and their Unbidden Guests for numerous other 

 structures and peculiarities of plants which are shown to be adaptive and 

 useful. 



