A Geological Retrospect of the Fear 1802. 151 



from the fancies of untenable theory. In his survey of these super- 

 ficial changes he was more particularly struck by the far-reaching 

 importance of those which result from the universal decay of the 

 surface of the land and the removal of the disintegrated material 

 to the bed of the sea. This impressive department of geological 

 science had attracted attention from an early period, and had been 

 especially studied by more than one observer during Lamarck's 

 lifetime. His great contemporary Button, for example, had made 

 it a cardinal feature in the scheme of his theory of the earth. The 

 French naturalist, however, though he was probably indebted to the 

 work of his predecessors, appears to have acquired a more vivid 

 appi'eciation than any of them of the several processes that con- 

 tribute towards the universal degradation of the dry land. He 

 perceived that nothing in Nature can ultimately resist the various 

 atmospheric influences which are ceaselessly at work upon every 

 portion of the earth's surface exposed to their attacks. But in his 

 little treatise he does not dwell on this part of his subject, contenting 

 himself with a brief enumeration of these influences, in which he 

 clearly distinguishes the effect of alternate wetness and dryness, of 

 heat and cold, and more particularly of frost. The general effect 

 of the combined operation of these subaerial agencies is pronounced 

 by him to be the ultimate destruction of every aggregation of 

 mineral matter, although the rate of advance of this disintegration 

 must greatly vary, according to the nature and condition of the 

 materials on which it acts (pp. 10, 11). 



In one important respect Lamarck's outlook upon Nature differed 

 from that of any previous or contemporary observer who occupied 

 himself in the study of geological processes. Before his time it was 

 the inorganic series of these processes which almost exclusively 

 received attention. But Lamarck was led to contemplate the whole 

 subject from the biological side. His long years spent in the 

 investigation of plants and his subsequent absorbing researches in 

 the animal kingdom had profoundly impressed him with the im- 

 portance of what he called the ' Pouvoir de la Vie ' — the power of 

 living organisms to build up substances and structures which could 

 have arisen through the operation of no inorganic agents. He had 

 already, in some of his published memoii's, called attention to this 

 great subject and formulated some of the conclusions to which he 

 had been led, and he now devoted to its discussion the longest 

 chapter of his little geological treatise. To him the processes of 

 life formed one of the grand elemental forces of Nature, independent 

 of but co-operating with the various physical agencies in building 

 up the materials of the terrestrial crust, and in effecting the constant 

 decay and reconstruction of the surface of the earth. It is only of 

 late years that the efficacy of plant and animal life, as a department 

 of dynamical geology, has been generally recognised, although we are 

 still far from having discovered all the various ways in which organic 

 bodies, living and dead, produce changes in the mineral kingdom. 



There can be no doubt that in this matter Lamarck realised far 

 more clearly than had ever been done before that the organic world 



