THE OUTER TISSUES OF PLANTS. 269 



observing how Bees come swarming into a house where 

 honey is largely exposed, or how Wasps find their way into 

 a shop containing much ripe fruit, it cannot be questioned 

 that insects are to a considerable extent guided by scent. 

 Being thus sensitive to the aromatic substances which flowers 

 exhale, they may, when the flowers are in large masses, be 

 attracted by them from distances at which the flowers them- 

 selves are invisible. And manifestly,, the flowers which so 

 attract them from the greatest distances, increasing thereby 

 their chances of efficient fertilization, will be most likely to 

 perpetuate themselves. That is to say, survival of the fittest 

 must tend to produce perfumes that are both more powerful 

 and more attractive. 



These physiological differentiations, then, which mark off 

 the foliar organs constituting flowers from other foliar organs, 

 are the consequences of indirect equilibration. They are not 

 due to the immediate actions of unlike incident forces on 

 the parts of the individual plant; but they are due to the 

 actions of such unlike incident forces on the aggregate of 

 individuals, generation after generation.* 



§ 276. The unity of interpretation which we here find for 

 phenomena of such various orders, could hardly be found 



* This seems as fit a place as any for noting the fact, that the greater part 

 of what we call beauty in the organic world, is in some way dependent on 

 the sexual relation. It is not only so with the colours and odours of flowers. 

 It is so, too, with the brilliant plumage of birds ; and it is probable that the 

 colours of the more conspicuous insects are in part similarly determined. The 

 remarkable circumstance is, that these characteristics, which have originated 

 by furthering the production of the best offspring, while they are naturally 

 those which render the organisms possessing them attractive to one another, 

 directly or indirectly, should also be those which are so generally attractive 

 to us — those without which the fields and woods would lose half their charm. 

 It is interesting, too, to observe how the conception of human beauty is in a 

 considerable degree thus originated. And the trite observation that the 

 element of beauty which grows out of the sexual relation is so predominant 

 in aesthetic products — in music, in the drama, in fiction, in poetry — gains a 

 new meaning when we see how deep down in organic nature this connexion 

 extends. 



