THE FUNCTION OF CONSCIOUSNESS. 515 



motion and sensibility have been preserved, and most 

 highly developed. 1 



We must remember, however, that in the matter 

 of the evolution of plant-types we have an especial 

 factor in the influence which insects have exerted on 

 the conditions of almost all of their organs. Insects 

 originated early in geological time, and have closely 

 accompanied plants in their evolution. As the source 

 of the food, and as the dwelling-places of great num- 

 bers of insects, they have been subjected to a class of 

 stimuli and strains similar to those which animals have 

 experienced. It is believed that the forms of the or- 

 gans of fructification and especially of the flowers, 

 have been greatly modified by the influence of insects.^ 

 The general evolution of plants, however, presents us 

 with a greater predominance of physiogenetic or simple 

 dynamical conditions over the bathmic, than in the case 

 of animals. Thus many peculiarities of the inflores- 

 cence directly result from the shortening of the axial 

 growth in complementary relation to the increase of 

 peripheral growth. Such is evidently the origin of 

 flowers themselves ; secondly of the umbel as com- 

 pared with the spike or panicle and finally of the com- 

 posite head as compared with the other modes of in- 

 florescence. To the cohesion of the elements of a 

 whorl, possible only in the case of an abbreviated axis, 

 can we ascribe the formation of a seed vessel from dis- 

 crete carpels, and a gamopetalous from a polypetalous 

 corolla. Degeneracy or specialization is to be seen 

 everywhere, as in the abortion of ovules, carpels, and 

 perianth. 



" Catagenesis of living organisms has been epito- 



\Origin of the Fittest, p. 428, 432- 

 2HensIow. 



