ORGANIC GEOLOGICAL DYNAMICS. 629 



Thus, we must have, as the direct productions o? 

 nature on this hypothesis, certain monads or rough 

 draughts, the primary rudiments of plants and ani- 

 mals. We must have, in these, a constant tendency 

 to progressive improvement, to the attainment of 

 higher powers and faculties than they possess; which 

 tendency is again perpetually modified and con- 

 trolled by the force of external circumstances. And 

 in order to account for the simultaneous existence 

 of animals in every stage of this imaginary progress, 

 we must suppose that nature is compelled to be 

 constantly producing those elementary beings, from 

 which all animals are successively developed. 



I need not stay to point out how extremely arbi- 

 trary every part of this scheme is; and how complex 

 its machinery would be, even if it did account for 

 the facts. It may be sufficient to observe, as others 

 have done 7 , that the capacity of change, and of 

 being influenced by external circumstances, such as 

 we really find it in nature, and therefore such as in 

 science w r e must represent it, is a tendency, not 

 to improve, but to deteriorate. When species are 

 modified by external causes, they usually degenerate, 

 and do not advance. And there is no instance of 

 a species acquiring an entirely new sense, faculty, 

 or organ, in addition to, or in the place of, what it 

 had before. 



Not only, then, is the doctrine of the transmu- 

 tation of species in itself disproved by the best phy- 

 7 Lyell, B. iii. c. iv. 



