cter than those imagined to exist by Cuvier, and which
certainly hold good for the vast majority of animals and plants, are of
universal application.

A bean may be supplied with water in which salts of ammonia and certain
other mineral salts are dissolved in due proportion; with atmospheric air
containing its ordinary minute dose of carbonic acid; and with nothing
else but sunlight and heat. Under these circumstances, unnatural as they
are, with proper management, the bean will thrust forth its radicle and
its plumule; the former will grow down into roots, the latter grow up
into the stem and leaves of a vigorous bean-plant; and this plant will,
in due time, flower and produce its crop of beans, just as if it were
grown in the garden or in the field.

The weight of the nitrogenous protein compounds, of the oily, starchy,
saccharine and woody substances contained in the full-grown plant and its
seeds, will be vastly greater than the weight of the same substances
contained in the bean from which it sprang. But nothing has been supplied
to the bean save water, carbonic acid, ammonia, potash, lime, iron, and
the like, in combination with phosphoric, sulphuric, and other acids.
Neither protein, nor fat, nor starch, nor sugar, nor any substance in the
slightest degree resembling them, has formed part of the food of the
bean. But the weights of the carbon, hydrogen, oxygen, nitrogen,
phosphorus, sulphur, and other elementary bodies contained in the bean-
plant, and in the seeds which it produces, are exactly equivalent to the
weights of the same elements which have disappeared from the materials
supplied to the bean during its growth. Whence it follows that the bean
has taken in only the raw materials of its fabric, and has manufactured
them into bean-stuffs.

The bean has been able to perform this great chemical feat by the help of
its green colouring matter, or chlorophyll; for it is only the green
parts of the plant which, under the influence of sunlight, have the
marvellous power of decomposing carbonic acid, setting free the oxygen
and laying hold of the carbon which it contains. In fact, the bean
obtains two of the absolutely indispensable elements of its substance
from two distinct sources; the watery solution, in which its roots are
plunged, contains nitrogen but no carbon; the air, to which the leaves
are exposed, contains carbon, but its nitrogen is in the state of a free
gas, in which condition the bean can make