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Of or pertaining to alburnum; of the alburnum; as, alburnous substances.

The part of a tree which lies immediately under the bark; the alburnum or sapwood.

The outer wood, the sapwood or alburnum, is of a pale yellow hue, and devoid of resin; the inner, the heartwood or duramen, which is by far the larger proportion, is of a dark greenish-brown, contains in its pores 26% of resin, and has a specific gravity of 1.333, and therefore sinks in water on which the alburnum floats.

If trees of one or five hundred years of age are cut down, the stumps are sure to throw up an immense number of sprouts from adventitious buds, as these are readily produced at almost any point on the sapwood or alburnum under the bark; and yet, with this inherent vitality and faculty of recuperation, the chestnut tree does not naturally, like many other deciduous kinds, throw up suckers from the roots.

The eggs deposited soon hatch, and the young larvæ bore through the tender bark at this point, and when fairly under it, branch off, cutting galleries through the soft alburnum underneath.