de mobilite et de croissance a succede une periode de stabilite, au moins
relative, une sorte d'age adulte, ou la force evolutive, ayant acheve son
oeuvre, n'est plus occupee qu'a la maintenir, sans pouvoir produire
d'organismes nouveaux. Limitee en quantite, comme toutes les forces en jeu
dans une planete ou dans un systeme sideral tout entier, cette force n'a pu
accomplir qu'un travail limite; et du meme qu'un organisme, animal ou
vegetal, ne croit pas indefiniment et qu'il s'arrete a des proportions que
rien ne peut faire depasser, de meme aussi l'organisme total de la nature
s'est arrete a un etat d'equilibre, dont la duree, selon toutes
vraisemblances, doit etre beaucoup plus longue que celle de la phase de
developpement et de croissance.


A fixed amount of "evolutive force" is given, to begin with. At first
enormous, because none has been used up in work, it is necessarily
enfeebled in the currents into which the stream divides, and the narrower
and narrower channels in which it flows with slowly-diminishing power.
Hence the limited although very unequal duration of all individuals, of all
species, and of all types of organization. A multitude of forms have
disappeared already, and the number of species, far from increasing, as some
have believed, must, on the contrary, be diminishing. Some species, no
doubt, have suffered death by violence or accident, by geological changes,
local alteration of the conditions, or the direct or indirect attacks of
other species; but these have only anticipated their fate, for M. Naudin
contends that most of the extinct species have died a natural death from
exhaustion of force, and that all the survivors are on the way to it. The
great timepiece of Nature was wound up at the beginning, and is running
down. In the earlier stages of great plasticity and exuberant power,
diversification took place freely, but only in definite lines, and species
and types multiplied. As the power of survival is inherently limited, still