188 VEGETATION AND THE ATMOSPHERE. 
bustion, and upon the same terms as do steam-machines; a force previously in- 
fused by the sun into plants, absorbed by them, virtually preserved in their 
products which are our sustenance, which we disengage by respiration and 
which our muscles apply under the direction of our wants and our will. This 
whole grand generalization of the phenomena of the world is the work of mod. 
ern chemists and physicists. It was MM. Dumas and Boussingault who first 
disengaged it; the mechanical theory of heat completed and demonstrated it; 
but it already existed entire in the conception of Lavoisier when he wrote: 
“Organization, spontaneous movement, life, exist only on the surface of the earth in 
places exposed to the light. It might be said that the fable of the torch of Prometheus was 
the expression of a philosophical truth which had not escaped the ancients. Without light 
nature would be without life—it would be dead and inanimate. A beneficent God, in sup- 
plying light, has spread over the surface of the earth organization, sentiment, and thought.” 
TY. 
If during the regular course of its existence, a vegetable accumulates organic 
matter, there are nevertheless two moments when it loses this essential character 
and comports itself like the animals: it is at the commencement and the end of 
its life, when it germinates and when it reproduces itself. very seed, besides 
the embryo which for long years preserves the principle of life, encloses a pro- 
vision of organic matter destined for the first nourishment of the springing plant. 
Cast on a warm and humid soil, it germinates; its radicle seeks in the soil a 
point of support and liquids; the germen rises upward; the seminal leaves or 
cotyledons are developed, and the rudimentary plant is established in virtue.of 
intrinsic and transmitted life. Now, during this first period, the provision of 
accumulated matter is divided into two parts: one is burnt by a sort of respira- 
tion, the other, undergoing complicated chemical actions, is transported into the 
organs and there becomes fixed inconstituting them. Everything occurs nearly 
as in an animal and without any intervention of light; but after this primitive 
phase, when the respiratory organs have received their first development, the 
plant waits for the rays of the sun to continue its evolution, and, as soon as 
these reach it, it inclines towards them as if eagerly to collect them, it becomes 
green, and commences, only to desist at its death, that decomposition of car- 
bonie acid and that accumulation of matter which is its function and its pre- 
destination. 
In order better to study this period of intrinsic life in the seed, M. Boussin- 
gault conceived the happy idea of prolonging it by indefinitely retarding the 
action of the light. The experiment was made with peas, in a soil without 
manure. After having germinated, they continued to grow, giving forth a pale, 
siender, creeping stem which at length perished without having borne seeds. 
During this whole period the peas continued to work up the organic material 
originally contained in the seed, and in proportion as their life was laboriously 
prolonged, they dispensed it by little and little in order to sustain it. At last, 
each plant had lost more than half the carbon which the seed had originally 
provided. While this experiment was going on in darkness, other peas, sowed 
at the same time, were successively transferred into the light. From that 
moment everything became changed; real life was developed, and the plant, 
being now able to avail itself of the nourishment contained in the air, gained 
each day, in the sun, very nearly as much carbon as it had previously con- 
sumed in darkness. 
In nature all things touch upon one another: vegetables in the seed, animals 
in the egg, appear to accomplish the same acts and exist in the same conditions. 
In both cases, a mass of organic matter accompanies the germ; the egg and 
the seed may preserve for an indeterminate length of time the virtual principle 
of life. A little heat will commence the evolution, and from that moment the 
