Page:An introduction to physiological and systematical botany (1st edition).djvu/68

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OF THE MEDULLA OR PITH.

centre or heart of the vegetable body, within the wood, contains the Medulla or Pith. This, in parts most endued with life, as roots, and young growing stems or branches, is a tolerably firm juicy substance, of an uniform texture, and commonly a pale green or yellowish colour. Such is its appearance in the young shoots of Elder in the spring; but in the very same branches, fully grown, the pith becomes dry, snow-white, highly cellular, and extremely light, capable of being compressed to almost nothing. So it appears likewise in the common Red or White Currant, and numerous other plants. In many annual stems the pith, abundant and very juicy while they are growing, becomes little more than a web, lining the hollow of the complete stem, as in some