THE PALM-STEM.

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tions directed toward a common centre, and by the simpleseparation of these subdivisions, it becomes decomposedinto just so many bundles containing all the essential partsof the vascular bundle.

From the character of the vascular bundle, as abovedescribed, follows incontrovertibly the total falsity of thegenerally received opinion, that the thicker and firmervascular bundles lying in the outer parts of the stem arethe older and lignified, and that the softer, lying in themiddle, are the younger, not yet come to their completedevelopment.

Modifications of the Structure of the Vascular Bundle invarious Balm-stems*

Although the structure of the vascular bundle exhibitsa common type in all Palms, modifications occur in thedifferent species.

In the cane-like stems, the liber of the outer hardlayer of the stem displays a very considerable develop-ment ; toward the centre it, indeed, diminishes again involume, yet still retains a moderate size, and since thethe vascular bundles are not very distinct from eachother, the middle of the stem possesses tolerable solidity.

In the cylindrical stems, the liber of the outer layers ex-hibits the greatest development that occurs in the Palms,into a mass ‘often elongated in the direction from withinoutwards ; in the middle of the stem the vascular bundleacquires an herbaceous softness, partly through the dimi-nution of the liber-bundle, partly through the walls ofits cells becoming so very thin, that in a cross sectionthey resemble parenchyma-cells.

In the cocos-like stems the liber only increases slowlyin the passage of the vascular bundle from the fibrouslayer toward the interior, and does not attain any con-siderable size; the vascular bundles of the outer parts of

* This portion consists of extracts, since the detail in the original referredto the illustrations. (H. v. Mohl.)