. A survey of the evolution of life suggests
to us a certain conception of knowledge, and also a certain metaphysics,
which imply each other. Once made clear, this metaphysics and this
critique may throw some light, in their turn, on evolution as a whole.

FOOTNOTES:

[Footnote 51: This view of adaptation has been noted by M.F. Marin in a
remarkable article on the origin of species, "L'Origine des especes"
(_Revue scientifique_, Nov. 1901, p. 580).]

[Footnote 52: De Saporta and Marion, _L'Evolution des cryptogames_,
1881, p. 37.]

[Footnote 53: On fixation and parasitism in general, see the work of
Houssay, _La Forme et la vie_, Paris, 1900, pp. 721-807.]

[Footnote 54: Cope, _op. cit._ p. 76.]

[Footnote 55: Just as the plant, in certain cases, recovers the faculty
of moving actively which slumbers in it, so the animal, in exceptional
circumstances, can replace itself in the conditions of the vegetative
life and develop in itself an equivalent of the chlorophyllian function.
It appears, indeed, from recent experiments of Maria von Linden, that
the chrysalides and the caterpillars of certain lepidoptera, under the
influence of light, fix the carbon of the carbonic acid contained in the
atmosphere (M. von Linden, "L'Assimilation de l'acide carbonique par les
chrysalides de Lepidopteres," _C.R. de la Soc. de biologie_, 1905, pp.
692 ff.).]

[Footnote 56: _Archives de physiologie_, 1892.]

[Footnote 57: De Manaceine, "Quelques observations experimentales sur
l'influence de l'insomnie absolue" (_Arch. ital. de biologie_, t. xxi.,
1894, pp. 322 ff.). Recently, analogous observations have been made on a
man who died of inanition after a fast of thirty-five days. See, on this
subject, in the _Annee biologique_ of 1898, p. 338, the resume of an
article (in Russian) by Tarakevitch and Stchasny.]

[Footnote 58: Cuvier said: "The nervous system is, at bottom, the whole
animal; the other systems are there only to serve it." ("Sur un nouveau
rapprochement a etablir entre les classes qui composent le regne
animal," _Arch. du Museum d'histoire naturelle_, Paris, 1812, pp.
73-84.) Of course, it would be necessary to apply a great many
restrictions to this formula--for example, to allow for the cases of
degradation and retrogression in which the nervous system passes into
the background. And, moreover, with the nervous system must be included
the sensorial apparatus on the one hand and the motor on the other,
between which i