result of cell-life--that gum and sugar are converted into the
organizable portion of the nutritious sap by the cells of the leaves.
The starchy fluid in the grains of corn is rendered capable of nutrition
to the embryo by the development of successive generations of cells,
which exert upon it their peculiar vitalizing influence. Albumen is
converted into fibrine by the vital agency of cell life--_i.e._, cells
are produced which do not form an integral part of any permanent
structure in the plant, but which, after attaining a certain maturity,
reproduce themselves and disappear; hence it may be stated that all the
vegetable productions which are formed in the plant are effected by a
series of vital actions through the agency of cells.

From the different transformations which these undergo all the different
tissues in vegetables are formed; for instance, the spiral and dotted
ducts, woody fibre, and so on. Schwann showed that the formation of
tissues in animals went through exactly the same progress, a fact which
has been confirmed by the microscopic observations of Valentin and
Barry. Thus vessels, glands, the brain, nerves, muscles, and even bones
and teeth are all formed from metamorphosed cells. Dr Bennett says--"If
this be true, and there can be little doubt, it obliges us to modify our
notions of organization and life. It compels us to confess that
vegetables and animals are not simple beings, but composed of a greater
or less number of individuals, of which thousands may exist in a mass
not larger than a grain of sand, each having a vital centre and separate
life, independent of those around it. Each of these individuals, or
organized cells, should be regarded as a living being, which has its
particular vital centre of absorption, assimilation, and growth, and
which continues to vegetate, to increase, and undergo transformations as
if it were an isolated individual. At all events, a knowledge of the
existence of the cell-life of plants will explain several phenomena
respecting the vegetation, growth, and ripening of corn, and may
hereafter lead to some valuable practical results."

_The climate, elevation, and exposure_ are not to be neglected. Upon the
higher portions of the Wolds crops suffer, much from elevation and
exposure, while in the western portion of Yorkshire, upon the moor
edges, the harvest is usually a month later than in the central parts of
the island.

_A moderate depth_ of soil in general is a