197 
the Embryo and Seedling in the Gramineae . 
diameter which passes through px v This diameter cuts the similar group 
px z , which lies on the other side of the centre, but nearer to it than px v As 
in Sorghum and Zea^ px z represents the protoxylem of midrib trace M , and 
is similarly situated. But Coix differs from Sorghum and Zea in the 
absence of an intermediate group of protoxylem on this diameter (px 2 
in Text-fig. 21). We have interpreted this group in Sorghum and Zea as 
common to the two groups of metaxylem on either side of px v In Coix 
each of these metaxylem groups has its own group of protoxylem, placed 
just within it, at a considerable distance on either side of the diameter 
of symmetry. The two groups are marked px 2 and px\ in Text-fig. 24. 
m 
Text-fig. 24 Coix Lacryma-Jobi , L. Diagram of mesocotyl as seen in transverse section. 
The contribution of the scutellum trace to the stele of the mesocotyl is 
therefore the protoxylem group px x , and part of the two phloem crescents 
on either side of it. When each crescent settles down into two distinct 
groups, ph x and ph 2 on one side, ph\ and ph\ on the other, it is natural to 
identify ph x and ph\ with the two halves of the scutellum phloem. The 
other constituents of the stele cannot be identified until they have been 
followed to the first node. 
We have series through the first node from two seedlings only, but 
both of them are complete and well differentiated. Some obscurity is 
introduced by the insertion of three cauline roots, but the midrib trace M 
can be followed into the stele of the mesocotyl, and the general course 
