a ditch or marsh this rush then pushes
out filiform stems which lie in the water, are there deformed,
becoming disturbed (_tracantes_), proliferous, and very different
from that of _Juncus bufonius_ which grows out of water. This plant,
modified by the circumstances I have just indicated, has been
regarded as a distinct species; it is the _Juncus supinus_ of
Rotte.[170]

"I could also give citations to prove that the changes of
circumstances relative to organisms necessarily change the
influences which they undergo on the part of all that which environs
them or which acts on them, and so necessarily bring about changes
in their size, their shape, their different organs.

"Then among living beings nature seems to me to offer in an absolute
manner only individuals which succeed one another by generation.

"However, in order to facilitate the study and recognition of these
organisms, I give the name of _species_ to every collection of
individuals which during a long period resemble each other so much
in all their parts that these individuals only present small
accidental differences which, in plants, reproduction by seeds
causes to disappear.

"But, besides that at the end of a long period the totality of
individuals of such a species change as the circumstances which act
on them, those of these individuals which from special causes are
transported into very different situations from those where the
others occur, and then constantly submitted to other influences--the
former, I say, assume new forms as the result of a long habit of
this other mode of existence, and then they constitute a new
_species_, which comprehends all the individuals which occur in the
same condition of existence. We see, then, the faithful picture of
that which happened in this respect in nature, and of that which the
observation of its acts can alone discover to us."

III. _Lamarck's Views on Species, as published in 1803._

In the opening lecture[171] of his course at the Museum of Natural
History, delivered in prairial (May 20-June 18), 1803, we have a
further statement of the theoretical views of Lamarck on species and
their origin. He addresses his audience as "Citoyens," France still
being under the _regime_ of the Republic.

The brochure containing this address is exceedingly rare, the only copy
existing, as far as we know, being in the library of the Museum of
Natural His