306 THE WORLD OF LIFE CHAP. 



disseminated ; I infer that this is the case from having as yet 

 found no exception to the rule that seeds are always thus 

 disseminated when embedded within a fruit of any kind if it 

 be coloured of any brilliant tint" l 



Such general statements as those here quoted do not 

 make much impression. The astonishment and delight of 

 botanists and plant-lovers can, therefore, be imagined when, 

 a few years later, by his book on the Fertilisation of Orchids 

 by Insects, and his papers on the Different Forms of 

 Flowers in the primrose, flax, lythrum, and some others ; 

 he opened up a vast new world of wonder and instruction 

 which had hitherto remained almost unnoticed. These were 

 followed up by his volumes on The Effects of Cross- and Self- 

 Fertilisation (in 1876), and by that on Different Forms of 

 Flowers on Plants of the same Species (in 1877), giving the 

 result of hundreds of careful experiments made by himself 

 during many years, serving as the justification for the few 

 general observations as regards flowers and insects, which 

 form the only reference to the subject in the Origin of 

 Species. 



The facts now admitted to be established by these various 

 researches are : (i) that crosses between different individuals 

 of the same species, either constantly or occasionally, are 

 beneficial to the species by increasing seed-production and 

 vigour of growth ; (2) that there are innumerable adaptations 

 in flowers to secure or facilitate this cross-fertilisation ; (3) 

 that all irregular flowers Papilionaceae, Labiates, Schrophu- 

 lariaceae, Orchideae, and others have become thus shaped to 

 facilitate cross-fertilisation. Darwin's general conclusion, 

 that " nature abhors perpetual self-fertilisation," has been 

 much criticised, but chiefly by writers who have overlooked 

 the term "perpetual." He has also shown how the wonder- 

 ful variety in form and structure, and the beauty or con- 

 spicuousness of the colours of flowers, can all be readily 

 explained, on this theory, through the agency of variation 

 and natural selection, while by no other theory is any real 

 and effective explanation possible. But besides these there 

 are very numerous other adaptations in flowers to secure 

 them from injurious insects or from the effects of rain or wind 



1 Origin of Species, 6th edition, p. 161. 



