50 THE PALM-ROOT: 



The connexion of the root with the stem takes place in 

 a manner wholly analogous; since in this also, in the 

 dissolution of the central body into single fibres, its 

 vessels are distributed into a great number of fine moni- 

 liform vessels. Those fibres penetrating the stem are, 

 indeed, formed for the most part of thin moniliform 

 vessels; but they nevertheless present an organization 

 tolerably resembling that of the vascular bundle of the 

 stem, for their vessels are surrounded by cellular tissue, 

 a little liber-bundle lies upon their outer side, and their 

 proper vessels occur between this liber-bundle and the 

 wood. 



I found the structure described, perfectly similar in the roots of a con- 

 siderable number of Palms, as might indeed be expected, since the said struc- 

 ture occurs almost as universally in the roots of Monocotyledons as the 

 above-described structure of the vascular bundles in their stems. 



This structure, however, is not without exceptions. I have already said 

 that in the upper parts of many Palm-roots, e. g. Phoenix, Cocos, fibrous 

 bundles are scattered through the rind, while no trace of them is found in 

 others. But the rather thick root of Iriartea exorUza exhibits more im- 

 portant deviations. A cross section of it presents to the naked eye a star 

 composed of brown lines, with obtuse, mostly bifid, rays. The microscope 

 shows that this star is formed of crowded vascular bundles. Besides these, 

 scattered vascular bundles occur singly in the centre of the star, but a central 

 cord, like that in the other Palm-roots, is wanting. The vascular bundles 

 have a structure totally unlike that of the vascular bundles of the stem, the 

 relative position of their organic systems being quite different. The liber- 

 bundle is directed towards the centre of the root, and in some of the vascular 

 bundles lying in the middle of the root, surrounds the woody portion. The 

 liber-tubes have thicker walls, and are more numerous in the outer bundles 

 than in those situated in the middle. The woody portion has 1, in rare 

 cases 2-3 large vessels, which in the outer bundles are &-& in the 

 inner, 77-73 f a line i n diameter. They are composed of longish tubes, 

 some have horizontal septa, some are without these ; their walls are covered 

 with little pores, placed in longitudinal rows ; where two vessels are in con- 

 tact, they have the form of scalariform ducts. They are surrounded merely 

 by 1-2 rows of parenchymatous cells. The outer side of this woody portion 

 is in contact with the parenchyma of the root. The bundles of proper vessels, 

 of which each vascular bundle contains one or two groups, consist, as in the 

 stem, of mingled, wide and narrow tubes. These do not lie between the 

 wood and liber, but in most cases on the outside of the liber-layer, half 



