Elements of botany, structural, physiological, systematical, and medical. Being a fourth edition of the Outline of the first principles of botany / By John Lindley.

  • John Lindley
Date:
1841
Catalogue details

Licence: Public Domain Mark

Credit: Elements of botany, structural, physiological, systematical, and medical. Being a fourth edition of the Outline of the first principles of botany / By John Lindley. Source: Wellcome Collection.

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    83. If a ligature be made round the bark, below a branch, the part above the ligature swells, that below it does not swell. 84. Therefore the matter which causes the increase of Exogenous plants in diameter descends. 85. If a growing branch is cut through below a leaf-bud, that branch never increases in diameter between the section and the first bud below it. 86. The diameter of all Exogenous stems increases in each species in proportion to the number of leaf-buds developed. 87. The greater number of leaf-buds above a given part, the greater the diameter of that part; and vice versa. 88. In the spring the newly forming wood is to be traced in the form of organic fibres descending from the leaf-buds; that which is most newly formed lying on the outside, and proceeding from the most newly developed buds. 89. Therefore the descending matter, by successive addi¬ tions of which Exogenous plants increase in diameter, pro¬ ceeds from the leaf-buds. 90. Their elongation upwards gives rise to new axes, with their appendages; their elongation downwards increases the diameter of that part of the axis which pre-existed, and pro¬ duces roots. 91. Roots, therefore, in all cases, should consist of exten¬ sions of woody tissue ; and this is conformable to observation. 92. Hence, while the stem is formed by the successive evolution of leaf-buds, the root, which is the effect of that evolution, has no leaf-buds. 93. The leaf-buds thus successively developed are firmly held together by the medullary system of the stem, which proceeds from the bark inwards, connecting the circumference with the centre. 94. The stem varies in structure in four principal ways. 95. It is either formed by successive additions to the out¬ side of the wood, when it is called Exogenous60 ; or by suc¬ cessive additions to its centre, when it is called Endogenous62; or by the union of the bases of leaves, and by addition to the point of the axis, or by simple elongation or dilatation where no leaves or buds exist; this is called Acrogenous. 96. In what are called Dictyogens^, the stem has the
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