308. =Buds of Plants in Winter.=--In the latter part of summer buds are formed on trees and shrubs, and these contain the germs of the branches, leaves, and flowers which are to come out the next year. These of course must be guarded against the cold of winter, and it is done very much as the pupa is guarded in the cocoon. Each bud you can see has a covering of scales which is air-tight, and inside of this there is a soft downy substance, the blanketing of the bud. In these coverings, which have been called by some one the "winter-cradles" of the buds, the infant vegetation of another year rocks back and forth in the wintry winds secure from the cold, till the warm sun of spring wakes its hidden life into activity. 309. =Snow a Protection to Plants.=--Snow is a good blanket to the earth, keeping its warmth from escaping into the cold air. This is because it contains mingled with its feathery crystals such a quantity of air. If snow come early, before the ground and the plants in it have become frozen, it will keep them from freezing through the winter, if it remain during all that time. It is curious to observe the peculiar arrangement of the snow in the arctic regions for the preservation of vegetation. First in the autumn come soft light snows covering up the grasses, and heaths, and willows. Then as winter advances there are laid on top of these the denser snows, making a compact, stout roof over the lighter snows in which the scanty but precious vegetation of those regions is imbedded. On top of this roof are deposited the snows of spring. As these melt the water runs off from the icy roof down the slopes, leaving untouched the plants underneath, which lie there alike secure from the rush of waters and from the nightly frosts until the season is sufficiently advanced to bring them out with safety from their concealment. Then the icy roof melts, and with it the light snows that have so long encircled the plants, and the sun wakes them from their long sleep to a new life.