Page:The Works of John Locke - 1823 - vol 03.djvu/338

 fibres of the roots being spread under ground, imbibe, from the moist earth, juice fit for their nourishment; this is conveyed by the stalk up into the branches and leaves, through little, and, in some plants, imperceptible tubes, and from thence, by the bark, returns again to the root; so that there is in vegetables, as well as animals, a circulation of the vital liquor. By what impulse it is moved, is somewhat hard to discover. It seems to be from the difference of day and night, and other changes in the heat of the air; for the heat dilating, and the cold contracting those little tubes, supposing there be valves in them, it is easy to be conceived how the circulation is performed in plants, where it is not required to be so rapid and quick as in animals.

Nature has provided for the propagation of the species of plants several ways. The first and general is by seed. Besides this, some plants are raised from any part of the root set in the ground; others by new roots that are propagated from the old one, as in tulips; others by offsets, and in others, the branches set in the ground will take root and grow; and last of all, grafting and inoculation, in certain sorts, are known ways of propagation. All these ways of increasing plants make one good part of the skill of gardening; and from the books of gardeners may be best learnt.

is another sort of creatures belonging to this our earth, rather as inhabitants than parts of it. They differ in this from plants, that they are not fixed to any one place, but have a freedom of motion up