hie Zoologique (1809), Lamarck first explicitly formulated
his ideas as to the transmutation of species, though he had outlined
them as early as 1801. In this memorable publication not only did he
state his belief more explicitly and in fuller detail than the idea
had been expressed by any predecessor, but he took another long forward
step, carrying him far beyond all his forerunners except Darwin, in
that he made an attempt to explain the way in which the transmutation of
species had been brought about. The changes have been wrought, he said,
through the unceasing efforts of each organism to meet the needs imposed
upon it by its environment. Constant striving means the constant use
of certain organs. Thus a bird running by the seashore is constantly
tempted to wade deeper and deeper in pursuit of food; its incessant
efforts tend to develop its legs, in accordance with the observed
principle that the use of any organ tends to strengthen and develop it.
But such slightly increased development of the legs is transmitted to
the off spring of the bird, which in turn develops its already improved
legs by its individual efforts, and transmits the improved tendency.
Generation after generation this is repeated, until the sum of the
infinitesimal variations, all in the same direction, results in the
production of the long-legged wading-bird. In a similar way, through
individual effort and transmitted tendency, all the diversified organs
of all creatures have been developed--the fin of the fish, the wing of
the bird, the hand of man; nay, more, the fish itself, the bird, the
man, even. Collectively the organs make up the entire organism; and what
is true of the individual organs must be true also of their ensemble,
the living being.

Whatever might be thought of Lamarck's explanation of the cause of
transmutation--which really was that already suggested by Erasmus
Darwin--the idea of the evolution for which he contended was but the
logical extension of the conception that American animals are the
modified and degenerated descendants of European animals. But people as
a rule are little prone to follow ideas to their logical conclusions,
and in this case the conclusions were so utterly opposed to the proximal
bearings of the idea that the whole thinking world repudiated them with
acclaim. The very persons who had most eagerly accepted the idea of
transmutation of European species into American species, and similar
limited variatio