, is still at the present day a living
and developing doctrine.

Lamarck's affinity with the transcendentalists was in many ways a close
one, but he differed essentially in being before all a systematist. Nor
is the direct influence of the German transcendentalists traceable in
his work--his spiritual ancestors are the men of his own race, the
materialists Condillac and Cabanis, and Buffon, whose friend he was. The
idea of a gradation of all animals from the lowest to the highest was
always present in Lamarck's mind, and links him up, perhaps through
Buffon, with the school of Bonnet. The idea of the _Echelle des etres_
had for him much less a morphological orientation than it had even for
the transcendentalists, for he was lacking almost completely in the
sense for morphology. Lamarck's scientific, as distinguished from his
speculative work, was exclusively systematic, and it was systematics of
a very high order. He introduced many reforms into the general
classification of animals. He was the first clearly to separate
Crustacea (1799), and a little later (1800) Arachnids, from insects. He
reduced to a certain orderliness the neglected tribes of the
Invertebrates, and wrote what was for long the standard work on their
systematics--the _Histoire naturelle des Animaux sans Vertebres_
(1816-22). His speculative work on biology is contained in three
publications, the small book entitled _Considerations sur l'organisation
des corps vivants_ (1802), the larger work of 1809, the _Philosophie
zoologique_, and the introductory matter to his _Animaux sans Vertebres_
(vol. i., 1816).

It is no easy matter to give in short compass an account of Lamarck's
biological philosophy. He is an obscure writer, and often
self-contradictory.

In the first part of the _Philosophie zoologique_ Lamarck is largely
pre-occupied with the problem of whether species are really distinct, or
do not rather grade insensibly into one another. As a systematist of
vast experience Lamarck knew how difficult it is in practice to
distinguish species from varieties. "The more," he writes, "we collect
the productions of Nature, the richer our collections become, the more
do we see almost all the gaps filled up and the lines of separation
effaced. We find ourselves reduced to an arbitrary determination, which
sometimes leads us to seize upon the slightest differences of varieties,
and form from them the distinctive character of what we call a species,
and at