21 I 
the Embryo and Seedling in the Gramineae . 
in length from o-8 mm. to about 1-5 mm. in the three seedlings from which 
we have fairly complete series. 
In seedlings of the age shown in Text-fig. 30, the first leaf has seven 
traces. The five larger run inwards at the second node, but each gives off 
one or two slender downward spurs before doing so. Hence a circle of 
seven or eight strands outside the stele of the first internode, in which the 
gap opposite the midrib is filled by the two marginal traces from the first 
leaf. These are still in their original position near the periphery of the 
section. They may unite to form a larger trace. 
The traces in the stele just above the first node are reduced to five, 
arranged in two groups. The cotyledonary traces run in from either side 
between these two groups. But as they do so, each strand or trace in the 
outer circle extends itself tangentially, in such a way that the two cotyle¬ 
donary traces are included in a vascular girdle which is concentric with the 
stele, but quite distinct from it. This girdle is shown in process of forma¬ 
tion in VI, Text-fig. 30. In the Elettaria seedling on whose structure 
these diagrams are founded, the xylem of the girdle is unlignified except at 
one point, but we have found a girdle much better differentiated in Amomum 
(PI. X, Fig. 13), and here the xylem is very well represented. The function 
of this girdle is probably to give rise to cauline roots, and its presence may 
indicate the approaching formation of a tuber. 
At the top of the hypocotyl, as soon as all traces of the first node have 
disappeared, there are four massive phloem groups, each very distinctly 
triangular in transverse section. Two of these are cotyledonary, and they 
are diagonally opposite to each other. The two groups which separate 
them are derived from the plumule. The arrangement of xylem is 
characteristic. All the protoxylem elements form a little group in the 
centre of the stele. The internal angles of the four triangular phloem 
groups are bordered by metaxylem for some distance up each side. In the 
oldest seedling examined, the xylem has the form of a four-rayed star. 
Each ray is double, for it consists of metaxylem border from each of two 
adjacent phloem groups, separated by a strip of medullary tissue. Even in 
this seedling it is clear that the metaxylem bordering the plumular 
phloem is formed of elements larger and better lignified than that which 
borders the cotyledonary groups. This difference is more clearly marked 
in the younger seedlings, where much cotyledonary xylem is still 
unlignified. 
Lower down, the symmetry of the stele alters, to provide for the inser¬ 
tion of cauline roots. The double rays become single by suppression of 
the medullary intervals, and then two parallel root-plates are formed from 
them. These root-plates are divided from each other by the cotyledonary 
bundles, which retain little or no metaxylem, but are each represented by 
a triangular patch of phloem and a small internal group of xylem elements, 
P % 
