A pine cone reaches maturity in two years; a single year suffices for the full development in Larix and several other genera.
How far "natural selection" suffices for the production of species remains to be seen.
If, however, a stiff autumn breeze be blowing, it suffices if the boy who formerly ran when the kite was let go stands still.
Since, however, only relatively low powers are now employed, the ordinary rack and pinion movement for focusing suffices, and for the illuminating the object only a mirror below the stage is required when the object is transparent, and a condensing lens above the stage when opaque.
For some cuttings, pots filled with light soil, with the protection of the propagating-house and of bell-glasses, are requisite; but for many of our hardy deciduous trees and shrubs no such precautions are necessary, and the insertion of a short shoot about half its length into moist and gritty ground at the proper season suffices to ensure its growth.
