46 THE PALM-ROOT. 



dance for the distance of some inches above the youngest 

 circle of roots, when the bark and fibrous layer are cut 

 open down to the vascular bundles. 



Anatomical Examination of the Hoot. 



The Palm-root is composed of two distinctly separated 

 layers an outer, looser, and spongy cortical substance, 

 and a tough, woody, central bundle. 



The cortical substance is coated by a parchment-like 

 membrane, under which lies a white spongy mass, in 

 which in some species lie liberous fibres ; in others these 

 are wholly wanting. Toward the extremity of the root, 

 and in the young side roots, this cortical layer is suc- 

 culent and compact ; in the older parts of the root it is 

 often half dried and more lax. The central bundle is 

 formed of a compact woody substance, which cannot be 

 separated into distinct individual bundles like the wood 

 of the stem. The central bundle of the side roots is 

 immediately connected with that of the main roots. 



When a root is traced backwards into the stem, it is 

 found that the cortical part of the root is considerably 

 diminished at its entrance into the cortical layer of the 

 stem, after a short distance disappearing by blending with 

 the cellular tissue of the stem. The central bundle, on 

 the contrary, penetrates the fibrous layer of the stem, and 

 spreads out on the outer layers of the wood-bundles of 

 the latter in the form of a disk. In its way through the 

 fibrous layer, it already begins to divide into several bun- 

 dles, separated by thin layers of cellular tissue. When 

 it arrives at the woody layer of the stem, it divides into 

 a great number of delicate filamentous bundles, which 

 run out in all directions like the rays of a star, and, 

 passing in serpentine course between the vascular bundles 

 of the stem, enter into its interior. They cannot be 

 traced more than about half an inch down between the 

 woody bundles, because they continually divide into 



