258 LAMARCK, HIS LIFE AND WORK 
obtain new faculties is aided by the concurrence of 
favorable circumstances; they create (créen?) with time 
the new organs which are adapted (propres) to their 
faculties, and which as the result develop after long use 
(gu'en suite un long emplot développe ). 
“Tow 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. 
“hey «can teadily convince themselves of the 
solidity of that which I have already published in 
this respect.* 
‘“Thave felt obliged to recall tosyou thesexereat 
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 sfeczes 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 mamme—you observe in the different 
orders which comprise this great series a gradation, 
shaded (xuancé), although irregular, in the composi- 
tion of the organization and in the i increasing number 
* Recherches sur [ Organisation des Corps vivans, p. 9. 
