ioo Spratt. — Some Anomalies in Monocotyledonous Roots. 
central cylinder is dilated and there is a concomitant differentiation of 
a number of scattered xylerp vessels and phloem strands on the inner side 
of the circle of radially arranged xylem and phloem strands. 
The material available in this investigation consisted of the roots of 
three species of Dracaena , namely, D. fruticosa, D. thalioides , and D . Draco ; 
Cordyline Shepherdii , Yucca filamentosa , Chamaerops macrocarpa , stilt roots 
of Pandamis , and aerial roots of Monstera deliciosa and Rapkidophora 
decursiva. It \ps fixed in chromacetic acid, and the investigation was 
carried out by means of hand sections and some microtomed ones stained 
with methyl green and fuchsin or water safranin and Erlich’s haema- 
toxylin. 
Dracaena. A series of transverse sections was cut through a root of 
Dracaena fruticosa from the tip upwards. In the younger part the sections 
show the structure of an ordinary Monocotyledonous root, i. e. polyarch. 
The protoxylems consist of from three to four vessels and the metaxylem 
vessels are not thoroughly differentiated since the walls are not lignified 
(see PI. Ill, Fig. i). The vascular elements are surrounded by cells, of 
which the walls gradually become thickened, so that there is apparently 
a sclerenchymatous.ring surrounding a pith. As the root matures new 
metaxylem vessels, distinguished by their large diameter, appear in the 
apparent sclerenchyma, and the phloem also increases somewhat in quantity 
and breaks up into very numerous small groups, some of which can be seen 
changing their position from the external to the internal periphery of the 
band of thick cells. Finally, groups consisting of either a metaxylem 
vessel surrounded by thick-walled cells, or a group of phloem surrounded 
by thick-walled cells, are detached from the band into the pith. Frequently 
these two different groups coalesce in the pith, either one phloem uniting 
with one xylem or two phloems with one xylem (see PL III, Fig. 3). 
Longitudinal sections revealed that the metaxylem vessels are somewhat 
peculiar. They have rather an unusual number of transverse walls to be j 
designated vessels, and yet these do not occur so frequently as is customary 
with tracheides, although the latter may be correlated with the fact that their 
diameter is larger than that of most tracheides. They have simple multi- 
seriate pits. The thick-walled cells surrounding these peculiar elements 
are tracheides of the normal type with simple pits scattered over their walls 
in irregular fashion (see PL III, Fig. 5). 
On investigation the root of Dracaena thalioides and D. Draco were 1 
found to exhibit the same peculiar characters as those of D. fruticosa. 
From the above description it will be evident that a kind of secondary 
growth takes place in the roots of these three species of Dracaena , since 
new xylem and phloem elements appear in the older roots which do not 
come from the primary meristems at the growing-points. There are three 
histogens, one giving rise to the plerome, another to the periblem and 
