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a plant or animal, or any part of a plant or animal — there are such 

 evident signs and proofs of a gradual and progressive development, 

 that we may believe this to have been an original principle, or a law 

 impressed in the constitution of our universe and of the beings by 

 which it is peopled. He first takes up the condition of the solar sys- 

 tem, before the formation of the planets, and traces the change of ne- 

 bulous matter into the sun and its planetary satellites ; all vehich, of 

 course, is purely hypothetical. 



In reading the past history of the earth, as unfolded to us by the 

 researches of geologists, we rest upon grounds that are something 

 more than hypothetical. It may be held a truth, inferred from suffi- 

 cient premises, that the earth has undergone great changes, in the 

 transition from its past to its present condition. There can be no 

 doubt that the earth was formerly inhabited by plants and animals 

 widely different from those at present existing upon it. It is proba- 

 ble, almost to certainty, that in the earlier condition of the globe, its 

 plants and animals were those of a simpler (" lower ") organization, 

 than some of the others which followed them ; although always, even 

 to the present times, animals and plants of an equally simple organi- 

 zation existed in abundance, along with those of a more complex 

 ("higher") organization. Such changes were apparently progressive, 

 proceeding generally from the simpler towards the more complex 

 types of structure : invertebrate animals preceding the vertebrate ; 

 fishes and reptiles preceding birds and beasts ; cryptogamic plants 

 preceding phanerogamic. 



A question naturally arises in any thoughtful mind, while contem- 

 plating these facts in their stony or earthy records, how plants and 

 animals were first called into being, and by what means the later spe- 

 cies were substituted in room of the earlier species ? It has been re- 

 peatedly suggested, that one or more species may have first emanated 

 from inorganic matter, and that succeeding species may have been 

 formed by mutation or metamorphose of the preceding species. This 

 hypothesis is plausible, to say the least of it. If adopted as a true 

 theory, it would account for much that is at present obscure or in- 

 comprehensible. It receives strong analogical support in those meta- 

 morphoses which are well known to take place during the progressive 

 development of individual plants and young animals. And there are, 

 moreover, some facts which bear so decidedly on the subject, as to 

 assume almost the character of direct evidence in confirmation of the 

 theory. 



