64 DR. D. H. SCOTT ON THE HETERANGIUMS 
two strands are about 1:2 mm. apart. The whole is evidently one leaf-trace, 
the two constituent bundles just dividing to form the four seen in traces 
further out. Lastly, just above the stele in fig. 1, we see two strands 
(Traee D) lying loose in the empty space between wood and perieycle. This 
tells us little, but in other sections the same pair is found in connection with 
the stele. This is shown in fig. 4, from the 3rd section below that from 
which fig. 1 was drawn. Here the two bundles are just detaching themselves 
from the wood of the stele, with which they are still in continuity. (See 
also Pl. 1. Phot. 1, which shows the same trace in an adjacent section.) 
We see, then, that in H. shorense two strands left the stele, that they 
divided into four in passing through the inner cortex, entered the leaf-base 
as a 4-bundle trace, and underwent further division in the petiole. The 
middle bundles, in fact, begin to show signs of division before the leaf-base 
separates from the stem. 
Although the available piece of stem was one and a half inches long, the 
changes in this length are but slight, and the comparison of the successive 
sections has only shown a fraction of the course of each leaf-trace. Thus, in 
the case of the four bundles entering a leaf-base (Trace A, fig. 1), the latter 
becomes decidedly more prominent as we follow the series upwards and more 
cut off from the cortex by selerenehyma. The bundles, however, are four in 
number all through, and, beyond moving outwards and showing some signs 
of further division, undergo little change. 
Trace B, which is somewhat difficult to follow owing to defects of preser- 
vation, is a 4-bundle trace from the bottom of the series ; following the trace 
upwards, the two pairs separate widely from each other, and those of each 
pair also diverge, but the stage shown in trace A seems not to be reached 
within the series. 
Trace C first appears as a 2-bundle trace, each bundle showing signs of 
division. The division becomes complete as we follow the trace upwards, 
but that is about the only change. 
The trace D, which is seen starting from the stele in the lower sections, 
cannot be followed continuously owing to damage. At the top of the series, 
however, what appears to be the same trace appears in the pericycle, each of 
the two bundles showing signs of division. 
Piecing together the evidence from the various traces, the whole course 
becomes clear, as explained above—namely, a double trace leaving the stele 
and further dividing into four bundles before entering the leaf-base. 
A word may be added as to the free petiole (fig. 2). It runs practically 
through the whole series, with little or no change. The transverse section 
measures about 12x 5:5 mm. It is concave on one side, convex on the other, 
the former having no doubt faced the stem. 
