86 BOTANICAL GAZETTE [FEBRUARY 
In Angiopteris (FARMER and HItt Q) certain cell rows in the 
solid protostele cease to differentiate as tracheids, and form a pith 
which rapidly increases in importance, for the leaf traces soon 
involve the whole thickness of the xylem ring. As soon as gaps 
are left, the annular appearance is lost, peripheral phloem dips 
down and borders the pith, and then internal endodermis is differ- 
entiated as a late and secondary occurrence. In Danaea (BREBNER 
3) what appears to be pith separates the xylem of the outgoing 
leaf traces from the stele, and the stem passes at once from the 
protostelic to the dictyostelic condition. 
In Marattia the protostele, usually solid at the cotyledonary 
node, may contain parenchyma cells, as in fig. 6. This is not 
definitely related to the center of the stele. When the first leaf 
trace goes off, a bay of the peripheral parenchyma may extend 
across the xylem. In this bay there may be isolated xylem elements 
which disappear later or join one or the other of the main xylem 
masses. The stele may become solid above and repeat the same 
process in giving off 4-9 more leaf traces, or it may contain scattered 
parenchyma from this time on. In the latter case the line of 
division for the next leaf trace is marked by the largest area of 
~ inclosed parenchyma. As in Danaea, a combination like the 
simultaneous departure of two or more leaves, or of a root and 
leaf, may give a temporary annular appearance (fig. 7), where the 
root trace (rt) is going off opposite the leaf trace (It). 
The stele may return to the solid protostele above such 4 
cylindrical stage. The first leaf traces may take off half of the 
elements of the protostele. Later, the stele increases in size 
proportion to the leaf traces, so that the line of division betwee? 
stele and leaf trace cuts in a curve instead of straight across the 
stele (text fig. 1). Phloem and endodermis close in behind the 
leaf trace over the concave as over the plane surface of the proto- 
stele (fig. 8). Soon a leaf trace goes off from the side opposite 
the curve before it has rounded out (fig. 9). This leaves tw° 
segments of the stele separated by parenchyma (fig. 10). The 
diagrams (figs. 11-21) show the start of the next leaf trace, the 
penetration of phloem into the stele from the opposite side (fgs- 
13-15), its withdrawal as the strands close together (fig. 16); 
