imal chain where are found the most simple organizations,
and that in considering among these organizations those whose
simplicity is so great that they lie at the very door of the
creative power of nature, then this same nature--that is to say, the
state of things which exist--has been to form directly the first
beginnings of organization; she has been able, consequently, by the
manner of life and the aid of circumstances which favor its
duration, to progressively render perfect its work, and to carry it
to the point where we now see it.

"Time is wanting to present to you the series of results of my
researches on this interesting subject, and to develop--

"1. What really is life.

"2. How nature herself creates the first traces of organization in
appropriate groups where it had not existed.

"3. How the organic or vital movement is excited by it and held
together with the aid of a stimulating and active cause which she
has at her disposal in abundance in certain climates and in certain
seasons of the year.

"4. Finally, how this organic movement, by the influence of its
duration and by that of the multitude of circumstances which modify
its effects, develops, arranges, and gradually complicates the
organs of the living body which possesses them.

"Such has been without doubt the will of the infinite wisdom which
reigns throughout nature; and such is effectively the order of
things clearly indicated by the observation of all the facts which
relate to them." (End of the opening discourse.)

APPENDIX (p. 141).

_On Species in Living Bodies._

"I have for a long time thought that _species_ were constant in
nature, and that they were constituted by the individuals which
belong to each of them.

"I am now convinced that I was in error in this respect, and that in
reality only individuals exist in nature.

"The origin of this error, which I have shared with many naturalists
who still hold it, arises from _the long duration_, in relation to
us, _of the same state of things_ in each place which each organism
inhabits; but this duration of the same state of things for each
place has its limits, and with much time it makes changes in each
point of the surface of the globe, which produces changes in every
kind of circumstances for the organisms which inhabit it.

"Indeed, we may now be assured that nothing on the surface of the
te