and absorb the crude aliment adapted to the needs of the plant to which
they belong, and the chlorophyl cells--the lungs and stomach of the
tree--in the leaves. During all the years of the growth of the plant,
these organs are mainly occupied in breaking the strongly riveted bonds
that unite oxygen and carbon in carbonic acid; appropriating the carbon
and driving off most of the oxygen. In the end, if the tree is, e. g.,
a _Sequoia_, some hundreds of tons of solid, organized tissue have been
raised into a column hundreds of feet in height, in opposition to the
force of gravitation and to the affinities of inorganic chemistry.

The time comes, however, sooner or later, when the power which has
created and the life that has pervaded this wonderful structure
abandon it. The affinities of inorganic chemistry immediately reassert
themselves, in ordinary circumstances rapidly tearing down the ephemeral
fabric.

The disintegration of organic tissue, when deserted by the force which
has animated and preserved it, gives rise to the phenomena which form
the theme of this paper.

Most animal-tissue decomposes with great rapidity, and plant tissue,
when not protected, soon decays. This decay is essentially oxidation,
since its final result is the restoration to the atmosphere of carbonic
acid, which is broken up in plant-growth by the appropriation of its
carbon. Hence it is a kind of combustion, although this term is more
generally applied to very rapid oxidation, with the evolution of
sensible light and heat. But, whether the process goes on rapidly or
slowly, the same force is evolved that is absorbed in the growth of
plant-tissue; and by accelerating and guiding its evolution, we are able
to utilize this force in the production at will of heat, light, and