244 LAMARCK, HIS LIFE AND WORK 



about the form of its body, the number and condition of 

 its organs, finally the faculties which it possesses. 



"Time and favorable circumstances are the two 

 principal means which nature employs to give exist- 

 ence to all her productions. We know that time 

 has for her no limit, and that consequently she has it 

 always at her disposition. 



" As to the circumstances of which she has need 

 {besoin) and which she employs every day to bring 

 about variations in all that she continues to produce, 

 we can say that they are in her in some degree in- 

 exhaustible. 



"The principal ones arise from the influence of 

 climate, from that of different temperatures, of the 

 atmosphere, and from all environing surroundings 

 {milieux) ; from that of the diversity of places and 

 their situations ; from that of the most ordinary 

 habitual movements, of actions the most frequent ; 

 finally from that of the meansi^^of preservation, of the 

 mode of life, of defence, of reproduction, etc. 



" Moreover, as the result of these different influ- 

 ences the faculties increase and strengthen themselves 

 by use, diversify themselves by the new habits pre- 

 served through long periods, and insensibly the .con- 

 formation, the consistence — in a word, the nature 

 and state of the parts and also of the organs — conse- 

 quently participate in all these influences, are pre- 

 t served and propagate themselves by generation " 

 ,{Systhne des Animaux salts Vertibres, p. 12). 



" It is easy for any one to see that the habit of 

 exercising an organ in every living being which has 

 not reached the term of diminution of its faculties 

 1 not only makes this organ more perfect, but even 

 ; makes it acquire developments and dimensions which 

 \ insensibly change it, with the result that with time 

 ' it renders it very different from the same organ con- 



