s
have presented an even and regular scale of development. But there has
been fresh water, salt water, running and stagnant water, warm and cold
climates, an infinite variety of depth: animals exposed to these and
other differences in their surroundings have varied in accordance with
them.[268] In like manner those animals which have been gradually fitted
for living in air instead of water have been subjected to an endless
diversity in their surroundings. The following law, then, may be now
propounded, namely:--

"_That anomalies in the development of organism are due to the
influences of the environment and to the habits of the creature._[269]

"Some have said that the anomalies above mentioned are so great
as to disprove the existence of any scale which should indicate
descent; but the nearer we approach species, the smaller we see
differences become, till with species itself we find them at times
almost imperceptible."[270]

Lamarck here devotes about seventy pages to a survey of the animal
kingdom in its entirety, beginning with the mammals and ending with the
infusoria. He points out the manner in which organ after organ
disappears as we descend the scale, till we are left with a form which,
though presenting all the characteristics of life, has yet no special
organ whatever. I am obliged to pass this classification over, but do so
very unwillingly, for it is illustrative of Lamarck, both at his best
and at his worst.

The seventh chapter is headed--

"On the influence of their surroundings on the actions and habits of
animals, and on the effect of these habits and actions in modifying
their organization."

"The effect of different conditions of our organization upon our
character, tendencies, actions, and even our ideas, has been often
remarked, but no attention has yet been paid to that of our actions and
habits upon our organization itself. These actions and habits depend
entirely upon our relations to the surroundings in which we habitually
exist; we shall have occasion, therefore, to see how great is the effect
of environment upon organization.

"But for our having domesticated plants and animals we should never have
arrived at the perception of this truth; for though the influence of the
environment is at all times and everywhere active upon all living
bodies, its effects are so gradual that they can only be perceived over
long periods of time.[271]

"Taking the chain of life in the inverse order o