THE PATH OF DEGENEEATION IN PLANTS 193 



recapitulation seldom occurs in plants, the develop- 

 ment of the whole and of its organs being usually 

 direct. When it does occur, it is generally limited 

 to characters coming from comparatively recent 

 ancestors and not even in the most transitory 

 form entering into the formation of the fundamental 

 parts of the plant. 1 



1 The rarity of recapitulation among vegetables is the result 

 partly of their fixed condition in the soil, and partly of the more 

 rigid nature of their cells. 



The immobility of a plant forces the adult to live in the same 

 place as the embryo. Among animals, on the other hand, it 

 frequently happens that the young pursue a manner of life 

 different from that of the adult and resembling that of the 

 ancestor. Young Cirrepedes are vagrant and have the same 

 needs and use the same organs as other vagrant Crustacea ; larval 

 frogs inhabit the water like their fish-like ancestors. In plants 

 there is nothing similar ; all the aquatic flowering plants are 

 derived from terrestrial ancestors, but if at the beginning of their 

 existence these aquatic plants were to bear leaves adapted to 

 aerial life they would ensure their own destruction. The ex- 

 ceedingly rare ancestral traits to be found in 'a few species are 

 naturally of a kind not to incommode their possessors. It is 

 improbable that these are a legacy from distant ancestors ; they 

 would not have been spared by natural selection had they not 

 come from ancestors of very much the same habit. The absence 

 of locomotion in plants has also produced a greater adaptability 

 than among animals. Animals, when conditions are unfavourable 

 can remove in search of more suitable localities, plants being fixed 

 in the soil must become modified or perish. Plants, therefore, 

 offer numerous cases of individual adaptation. We do not know 

 if these adaptations are transmitted by heredity, but natural 

 selection has at least secured the widest range of plasticity. 

 Thus plants rapidly rid themselves of ancestral legacies which 

 have become useless. 



The transitory organs of animals are employed for the service 

 N 



