The Anatomy of Palm-Roots. 21 
as experience goes, however, the distribution of procambial tissue 
{which is simply young vascular tissue) does not yield any evidence, 
which is better than or essentially different from that derived from 
the mature structure. 
Dr. Drabble (p. 452) concludes from his examination of the 
roots of Palms that “ the central cylinder in these organs is not the 
simple structure, which Van Tieghem considered the root-cylinder 
to be, and upon which he based his conception of monostely.” 
This conclusion is arrived at because the author traces the structure 
acropetally and expresses the normal root-cylinder in terms of the 
structure found in the basal region (describing it as formed by the 
fusion of separate strands)' without stopping to consider which 
region is likely to be the more specialized one. 
Now it is probable that the exact reverse of Dr. Drabble’s 
method would lead one nearer to the truth of the morphology. 
The structure of the more distal part of the root conforms in 
general features to the type found in other Monocotyledons, while 
the basal region of the root in palms appears to possess a spe¬ 
cialized structure in relation to the attachment of the large root- 
cylinder to numerous stem-bundles. Possibly the basal part of the 
root might be held to be an intercalated region, but it is more 
natural to regard its structure as having been attained by pro¬ 
gressive modification of the normal structure (in the basal region) 
following the increase in the number of the bundles of attach¬ 
ment, which must have accompanied increase in size of the stele 
of the root. In any case the normal structure of the root cannot 
be regarded as derived from a structure similar to that of the 
basal region, which must be treated separately or as a modification 
of normal structure. Dr. Drabble bases his morphological views 
chiefly on two kinds of evidence, the behaviour of the procambial 
strands and the acropetal sequence of tissues. As the first of these 
probably has no value and the second appears to be entirely mis¬ 
leading, the further theoretical conclusions based on similar data 
need not be specially referred to. 
The structure of the basal part of the root may, for descriptive 
purposes, be regarded as due to the breaking up of the root-stele 
into separate vascular arcs or cylinders. If one attempts a 
morphological explanation, one may hold that the morphology of 
the different tissues in this region is incapable of determination, the 
counterpart of this being found in the case of much specialised 
external members, or the structure may be partially and provi- 
