in distinction
to that of functional adaptation which interested Cuvier so greatly,
came vividly before him as he worked through the vast collections of the
museum. He was the first systematist to occupy himself in a
philosophical manner with the problems of general biology. He introduced
new problems and a new way of looking at old. With Lamarck the problem
of species and the problem of ecological adaptation enter into general
biology.

The one point in which he does definitely carry on the thought of his
predecessors is his conception of the animal kingdom as forming a scale
of (functional) perfection. He did not go to the same extreme as Bonnet;
he did not even consider that the animal series was a continuation of
the vegetable series; in his opinion they formed two diverging scales.
He recognised, too, that among animals there was no simple and regular
gradation from the lowest to the highest, but that the orderly
progression was disturbed and diverted by the necessity of adaptation to
different environments. It is interesting to note that in developing
this idea he arrived at a roughly accurate distinction between
homologous and analogous structures. More importance, he thought, was to
be attributed in classifying animals to characters which appeared due to
the "plan of Nature" than to such as were produced by an external
modifying cause (p. 299). But he did not formulate the distinction in
any strictly morphological way.

As his ideas developed he laid less stress upon the simplicity and
continuity of the scale; in his supplementary remarks to the
Introduction of 1816 he admits that the series is really very much
branched, and even that there may be two distinct series among animals
instead of one. His last schema of the course of evolution shows no
little analogy with the genealogical trees of Darwinian speculation. It
is headed "The presumed _Order_ of the formation of Animals, showing two
separate partly-branching series," and it reads as follows:--

I.--_Series of Non-articulated_ II.--_Series of Articulated_
_Animals_. _Animals_.
"
I |-- Infusoria.
n | |
s A | Polyps.
e n | |
n i | ----------------
s m | | |
i a | Ascidians. Radiates. Worms.
t l | | |
i s | | -