LAMARCK'S THEORY OF EVOLUTION 



253 



into very different situations from those, where the 

 others occur, and then constantly submitted to other 

 influences — the former, I say, assume new forms as 

 the result of a long habit of this other mode of exist- 

 ence, and then they constitute a new species, which 

 comprehends all the individuals which occur in the 

 same condition of existence. We see, then, the faith- 

 ful picture of that which happened in this respect in 

 nature, and of that which the observation of its acts 

 can alone discover to us." Y 



III. Lamarck's Views on Species, as published in 1803. 



In the opening lecture * of his course at the Mu- 

 seum of Natural History, delivered in prairial (May 

 20-June 18), 1803, we have a further statement of 

 the theoretical views of Lamarck on species and their 

 origin. He addresses his audience as " Citoyens," 

 France still being under the regime of the Republic. 



The brochure containing this address is exceed- 

 ingly rare, the only copy existing, as far as we know, 

 being in the library of the Museum of Natural His- 

 tory in Paris. The author's name is not even given, 

 and there is no imprint. Lamarck's name, however, 

 is written on the outside of the cover of the copy we 

 have translated. At the end of the otherwise blank 

 page succeeding the last page (p. 46) is printed the 

 words : Esquisse d'un Philosophie zoologique, the pre- 

 liminary sketch, however, never having been added. 



He begins by telling his hearers that they should 

 not desire to burden their memories with the infinite 



* Discours d'ouverture d'tm Cours de Zoologie, prononc^ en prairial, 

 an XI, au Museum d' Histoire naturelle, sur la question, Qu'est-ce 

 aue Vesphe parmi les cm-ps vivans? (1803). 



