1922] BLOMQUIST—ANGIOPTERIS IgI 
tion of vascular tissue is found to be related to the second leaf 
trace. The few tracheids which join up the first leaf stage with 
the second pass into the second root stele, while some pass directly 
upward and add to the structure of the second leaf trace (fig. 3 D, £). 
SECOND LEAF STAGE 
The second root appears slightly above the transition region, 
about 130° from the first leaf trace. Fig. 20 shows this root in a 
very young stage. It is impossible to state from what tissue this 
originates, since it appears before any differentiation of tissues has 
taken place. The same is also true of Maraitia. The second leaf 
trace appears directly above the second root. Some variation 
occurs at this stage; the second leaf trace may be joined to the 
third by both edges, in which a second tube is formed and the gap 
formed by the first leaf is repaired. In as many cases, however, 
only one edge is joined up with the third leaf trace, and in such 
cases the leaf gap is not repaired. In either case the phloem 
occurs on the inside as well as on the outside of the vascular tissue. 
The endodermis which was very evident in the first stage is more 
difficult to locate. Although endodermal thickenings occur, the 
characteristic organization is more or less broken up. In no cases 
was the vascular tissue observed to become a solid strand after 
the junction of the first and second leaf stages had been passed. 
In Marattia, on the contrary, the protostelic condition may appear 
more than once. 
THIRD LEAF STAGE 
After the second leaf stage has been passed, the vascular tissue 
of the central region never appears as a tube. The third root 
stele originates on the level with the outgoing of the second leaf 
trace from the central region. At this stage the leaf trace comes 
off from one edge of the central strand, which is the vascular tissue 
leading up to the fourth leaf trace (fig. 3 F-H). The latter tissue 
now assumes a. crescent-shaped form in cross-section. A few 
scattered tracheids may come off the free edge of the third leaf 
trace and wander back toward the central strand, or may end 
blindly before arriving there. These tracheids represent the 
rudimentary commissural strand, which in many cases is fairly 
