258 LAMARCK, HIS LIFE AND WORK 



obtain new faculties is aided by the concurrence of 

 favorable circumstances; they create (cr^ent) with time 

 the new organs which are adapted {propres) to their 

 faculties, and which as the result develop after long use 

 {qu'en suite un long emploi ddveloppe ). 



" How important is this consideration, and what 

 light it spreads on the state of organization of the 

 different animals now living ! 



" Assuredly it will not be those who have long been 

 in the habit of observing nature, and who have fol- 

 lowed attentively that which happens to living in- 

 dividuals (to animals and to plants), who will deny 

 that a great change in the circumstances of their 

 situation and of their means of existence forces them 

 and their race to adopt new habits ; it will not be 

 those, I say, who attempt to contest the foundation 

 of the consideration which I have just exposed. 



" They can readily convince themselves of the 

 solidity of that which I have already published in 

 this respect.* 



" I have felt obliged to recall to you these great 

 considerations, a sketch of which I traced for you 

 last year, and which I have stated for the most part 

 in my different works, because they serve, as you 

 have seen, as a solution of the problem which interests 

 so many naturalists, and which concerns the deter- 

 mination of species among living bodies. 



" Indeed, if in ascending in the series of animals 

 from the most simply organized animalcule, as from 

 the monad, which seems to be only an animated 

 point, up to the animals the most perfect, or whose 

 structure is the most complicated — in a word, up to 

 animals with mammae — you observe in the different 

 orders which comprise this great series a gradation, 

 shaded {nuanc^), although irregular, in the composi- 

 tion of the organization and in the increasing number 



* Recherches stir V Organisation des Corps vivans, p. 9. 



