312 STUDIES, SCIENTIFIC AND SOCIAL 



Adaptations not Explicahle on the Theory of Response 

 to Irritation. 



A few remarks may now be added on the general ques- 

 tion of adaptation in the vegetable kingdom. Reference 

 has already been made to the numerous cases in which 

 the special adaptations of flowers to insect-fertilisation 

 can by no stretch of imagination be iniputed to the direct 

 action of insects, and the same thing is equally clear in 

 many other directions. The whole group of insectivorous 

 plants, for instance, exhibit strange and complex adapta- 

 tions which have no direct relation to the mere fact of 

 insects crawling over them or settling upon them. So 

 also are those varied adaptations by which, as Kerner has 

 shown, injurious insects are prevented from reaching the 

 flowers. 



Even more unintelligible on this theory are modifica- 

 tions of fruits and seeds, by which some attract birds or 

 mammals to eat them, while others are guarded against 

 being eaten ; some seeds have beautiful wings or plumes 

 for wind dispersal, others have hooks or sticky hairs which 

 cling to wool or feathers, while others again are scattered 

 abroad by the sudden elastic bursting of the capsules. 

 Take the comparatively simple case of niits. Did they 

 acquire their hard covering and brown protective tints 

 and detachment from the tree as soon as ripe by the direct 

 agency of birds, or monkeys, or squirrels ? Of course, the 

 question is absurd, since those eaten by these creatures 

 could not transmit their special qualities ; but those that, by 

 the possession of any of these qualities, escaped being eaten, 

 would transmit those qualities to the next generation.^ 



Any conceivable direct action of the environment can 

 therefore have produced only a very small portion of the 

 modifications and adaptations that actually exist. In by 



the Mediterranean district, and he adds: "In northern regions not 

 exposed to summer drought, where grazing animals find in summer 

 enough green fodder, this form of plant is almost entirely absent," 

 {The Natural History of Plants, English Translation, vol. i., p. 445.) 



^ Other cases of the want of relation between adaptations and their 

 supposed cause are given in the next chapter. 



