Observations on the Nature and Importance of Geology. ^7 



himself in the most unambiguous manner. He admits, on the 

 one hand, the existence of the simplest infusory animals ; oil 

 the other, the existence of the simplest worms, by means of 

 spontaneous generation, that is, by an aggregation process of 

 animal elements ; and maintains, that all other animals, by the 

 operation of external circumstances, are evolved from these in 

 a double series, and in a gradual manner. On that account, 

 the scale of gradation, according to which he arranges the ani- 

 mal kingdom, is, at the same time, the history of their origin ; 

 and the discovery of this truly natural method, the most im- 

 portant problem of the natural philosopher. Although it should 

 not be forgotten, that this meritorious philosopher, more in con^ 

 formity with his own hypothesis than is permitted in the pro- 

 vince of physical science, has resigned himself to the influence 

 of imagination, and attempted explanations, which, from the 

 present state of our knowledge, we are incapable of giving, we 

 nevertheless feel ourselves drawn towards it, and these notions 

 of the progressive formation of the^ organic world, must be 

 found more worthy of its first Great Author than the limited 

 conceptions that we commonly entertain. 



Geology can alone inform us, how far this successive course 

 of development may have been followed by nature. When all 

 the races of animals, whose remains are contained in the crust 

 of the earth, have been better ascertained than at present, and 

 their situations better kno^vn, when we have discovered at what 

 period of the earth's formation any species of animals makes its 

 appearance for the first time, we shall then be able to draw con- 

 clusions, more or less accurate, concerning the order of succes- 

 sion. The doctrine of petrifactions, even in its present imper- 

 fect condition, furnishes us with accounts that seem in favour of 

 Mr Lamarck''s hypothesis. We, in fact, meet with the more 

 perfect classes of animals, only in the more recent beds of rocks, 

 and the most perfect, those closely allied to our own species, only 

 in the most recent ; beneath them occur granivorous, before car- 

 nivorous, animals ; and human remains, are found only in allu- 

 vial soil, in calcareous tuff, and in limestone conglomerates. 



Geology does not inform us merely of the origin of animal 

 species, but also of their destruction. Out of the vast number 



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