ditation to action. "He at length put forward his opinion in
1825, he returned to it, but still briefly, in 1828 and 1829, and did
not set himself to develop and establish it till the year 1831--the year
following the memorable discussion in the Academy, on the unity of
organic composition."[324]

"If," says his son, "he began by paying homage to his illustrious
precursor, and by laying it down as a general axiom, that there is no
such thing as fixity in nature, and especially in animated nature, he
follows this adhesion to the general doctrine of variability by a
dissent which goes to the very heart of the matter. And this dissent
becomes deeper and deeper in his later works. Not only is Geoffroy St.
Hilaire at pains to deny the unlimited extension of variability which
is the foundation of the Lamarckian system, but he moreover and
particularly declines to explain those degenerations which he admits as
possible, by changes of action and habit on the part of the creature
varying--Lamarck's favourite hypothesis, which he laboured to
demonstrate without even succeeding in making it appear probable."[325]

Isidore Geoffroy then declares that his father, "though chronologically
a follower of Lamarck, should be ranked philosophically as having
continued the work of Buffon, to whom all his differences of opinion
with Lamarck serve to bring him nearer."[326] If he had understood
Buffon he would not have said so.

His conclusions are thus summed up:--"Geoffroy St. Hilaire maintains
that species are variable if the environment varies in character;
differences, then, more or less considerable according to the power of
the modifying causes _may have_ been produced in the course of time, and
the living forms of to-day _may be_ the descendants of more ancient
forms."[327]

It is not easy to see that much weight should be attached to Geoffroy
St. Hilaire's opinion. He seems to have been a person of hesitating
temperament, under an impression that there was an opening just then
through which a judicious trimmer might pass himself in among men of
greater power. If his son has described his teaching correctly, it
amounts practically to a _bona fide_ endorsement of what Buffon can only
be considered to have pretended to believe. The same objection that must
be fatal to the view pretended by Buffon, is so in like manner to those
put forward seriously of both the Geoffroys--for Isidore Geoffroy
followed his father, but leant a little m