1020 
Scott . — The Structure of 
As regards the outward course of the leaf-traces, there is no essential 
difference from M. Sutcliffii. The bundles, however, run very obliquely 
through the secondary wood, the phloem zone, and the inner cortex ; they 
are seldom seen well in transverse sections of these regions. We know, 
however, that the origin d pair divided up into eight, for all the eight 
bundles of a trace are seen in the section shown in PL XC, Fig. 24, where 
they are entering a leaf-base. Some sections show the strands passing 
almost horizontally through the wood, and subdividing as they enter the 
cortex. 
The structure of the primary strand is essentially the same as in 
M. Sutcliffii and other species. The centripetal xylem is perhaps rather 
specially well developed ; here also the protoxylem, where it can be clearly 
seen, is in contact with the centripetal part of the xylem, abutting on the 
internal parenchyma of the strand (PL XC, Fig. 23). Longitudinal sections 
show that the centripetal wood is composed, apart from the protoxylem, 
of close-wound spiral elements. The somewhat oblique tangential section 
from which the photograph (PL LXXXVIII, Figs. 11 and 12) is taken 
shows a pair of bundles approaching the pith. In the right-hand bundle 
the plane of section passes obliquely through the island of parenchyma and 
protoxylem (Fig. 12 ,px.). 
No actual sheath is developed round the xylem -strands as they reach 
the pith. There is, however, a very near approach to this structure, for, 
where the double strand is entering through the wood and getting near the 
pith, the adjacent cells on the inner side have divided tangentially, and 
some of them show tracheal markings, just as in M. Lomcixii (Fig. 9, sh). 
The differences between the two species as regards the bundle-sheath is thus 
only one of degree. 
The Wood. 
The inner part of the centrifugal wood is composed of spiral, reticulate, 
or scalariform elements. The reticulate markings are often evidently 
formed by crossed spiral bands, such as are shown at one or two places in 
Mr. Maslen’s figure from a leaf-trace bundle of M. Sutcliffii (Maslen, Tl, 
PI. XXXV, Fig. 14). The reticulate condition often forms the transition 
to the regular pitted sculpturing of the main mass of secondary tracheides. 
The zone of spiral and transitional elements is of considerable width, twelve 
to fourteen layers in the leaf-trace, and about six layers even where the 
wood appears to be purely secondary. This seems to be a specific difference 
from M. Lomaxii. 
The typical, pitted, secondary tracheides have only two rows of pits on 
the radial wall, and sometimes only a single row (PL LXXXVIII, Figs. 
14 and 16). Where a medullary ray is crossed, the pits are more numerous, 
narrower, and markedly oblique. The tracheides are about 20 to 40 /x in 
