37 
Edith Chick on Torreya Myristica . 
are in the positions of the late protoxylem groups, i.e. in the 
positions horn which the cotyledon traces will go out. Secondary 
xylem is now formed in these two places by the cambium, and 
the metaxylem patch is in contact with secondary xylem here, as 
elsewhere at the periphery of the pith (Fig. 8). The phloem is 
continuous across the former gap, while the true endodermis and 
the “false endodermis” with globular thickenings alike disappear. 
(The outermost layer of the pericyclic periderm has here elongated 
radially, and has also become suberized, so that at first sight it 
might be taken for an endodermis.) 
Character of the Cotyledon-Trace on its passage out. 
The cotyledon trace in the hypocotyl corresponds in position with 
that of the root protoxylem. The trace consists of some secondary 
xylem formed from the trace-cambium, some primary, and some 
protoxylem elements which stretch inwards in bands and come in 
contact at certain places with the continuations of the root plate; 
these I propose to call for purposes of convenience and description, 
metaxylem strands (nix). In the transition region they have the 
position already described, and consist of scalariform tracheides, 
but when the cotyledonary bundles are formed those opposite to 
it, i.e., in the two root-protoxylem regions, soon shew a change, 
so that among them, and at first between them and the secondary 
xylem of the ring, later between them and the true protoxylem of 
the cotyledon trace, smaller elements appear, which are seen in 
longitudinal section to be spiral and annular. This stage is shewn 
diagrammatically in PI. viii., figs. 8 and 9. The appearance of the 
strand as shewn in fig. 8, reminds one of an exarch bundle, and the 
presence, as will be described later, of a large quantity of centri¬ 
petal xylem in the lamina and petiole of the cotyledon, would seem 
at first to lend a good deal of significance to this state of affairs, 
and in consequence the strand was followed carefully into the 
cotyledon petiole, by means both of transverse and longitudinal 
sections. In longitudinal section these strands are seen to consist 
more and more of spiral and annular elements ; till, as the cotyle¬ 
donary node is approached, and they finally pass out into the petiole, 
still in contact with the trace-protoxylem, they are entirely formed 
of typical protoxylem elements. 
Summary of Transition. 
The root-protoxylem dies out below the cotyledonary node ; 
and the protoxylem which accompanies the cotyledon trace out- 
