ANATOMY OF THE ROOTS OF PALMS, 429 
the lateral roots in. certain cases run through: the cortex of the parent root for some 
distance before emerging. He finds three meristematic layers in the root-apex of 
Kentia Forsteriana, viz.: one for the plerome, one common to periblem and zz derma- 
togen,” and one for the root-cap. 
Outline of Results of the present Investigation. 
Mangin’s account of the presence of many deeply penetrating strands of xylem and 
phloem establishing connection with the bundles of the stem is confirmed. These are 
traced into the apex of the young root as separate strands with such protoxylem as they 
. possess arranged in an exarch manner, roughly alternating with phloem-groups. It is 
shown that these procambial strands, consisting of fibrous tissue enclosing xylem and 
phloem elements, are developed in a common ground-tissue at the non-stratified apex of 
the root, and that as development proceeds the more peripheral of these strands become 
arranged in what is at first an incomplete ring, passing distally into first a lobed 
cylinder, and finally into the normal cylinder of the root. All these stages are due to 
progressive changes in the procambial tissue of the meristematic apex. 
Some of the more internal procambial strands do not enter into the fibrous ring, but 
persist as the well-known medullary strands, each presenting proximally a radial 
structure, with xylem and phloem well developed, but reduced distally, so that we find 
(i.) strands containing a few vessels only, accompanied by one or more phloem-groups ; 
(i) one or two large vessels and a few smaller ones, unaccompanied by phloem ; 
and (iii.) a single large vessel without accompanying smaller vessels or phloem. 
All eases examined show the presence of a central cylinder composed of separate 
strands, passing into the lobed cylinder (7. e., Cormack’s Areca-type) in that portion of 
the root which runs through the cortex of the stem. 
Usually the apex undergoes complete simplification while passing through the 
cortex of the stem, resulting in the production of a normal root cylinder, and hence the 
external root is normal; but in certain cases (e. g., Areca, Keniia, &e.) the simplification 
is much more gradual, the external root exhibiting the completely separate strands, as 
in Areca sp., or the lobed cylinder, as in Kentia sp. 
In eonsideration of the method of development, it is claimed that the idea of a pith 
as a separate morphological entity is entirely precluded, the central parenchyma being 
merely that portion of the common ground-tissue which becomes enclosed by the 
gradually approximating and finally uniting procambial strands ofthe apex; it is 
always in complete continuity with “ cortical” parenchyma proximally. 
Buscalioni’s account of the centrifugal appearance of the xylem elements of the 
bundle in roots of Monocotyledons, followed by the centripetal lignification, is confirmed 
for the palms; and the large scattered internal vessels of the fibrous cylinder are 
shown to be the persisting metaxylem elements of strands whose protoxylem has 
aborted. 
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