774 PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE 
pericycle contain numerous sclerotic groups. X 6. From a new specimen 
(in the possession of D, H. Scorr), obtained through Professor Bower, 
F.R.S., from Oldham (see pp. 706 and 708). 
Fig. 2. Part of transverse section from the same specimen as Plate 18, photograph 1, 
showing the xylem-strand marked w.? in that photograph. The mesarch 
structure is evident. px., protoxylem; «., centripetal portion of primary 
wood; x.!, centrifugal portion of the same ; x.®, part of secondary wood; 
14 Mu, TAYS} P., p-, pith; s.s., secretory sac. X 100. C.N. 1884 (see pp. 709 
and 712). 
Fig. 8. Another section from the same specimen, showing the large double xylem- 
strand, marked w.° in photograph 1. Lettering as in fig. 2. x 100. C.N. 
1640 (see pp. 709, 711, and 712). (C.N. 1640 and 1884 are adjacent and 
practically identical sections from the same stem.) 
PLATE 22. 
Fig. 4. Part of a radial section, passing through one of the primary xylem-strands, 
and showing mesarch structure. Lettering as in figs. 2 and 3. X 100. 
C.N. 1982 (see p. 712). 
Fig. 4a. Parts of secondary tracheides from same section, to show bordered pits. 
x 150. 
Fig. 48. Ditto in tangential section. 7., secondary rays. X 150. C.N. 1985 (see 
p- 716). 
Fig. 5. Part of transverse section showing the leaf-trace bundle, marked /.t.' in photo- 
graph 1, illustrating the collateral mesarch structure. pz., pa., the two 
protoxylem-groups of the bundle ; «., centripetal part, #.’, centrifugal part, 
of its primary wood ; x.”, secondary wood of bundle ; cb.”, its cambium ; ph.”, 
its phloém ; .?, secondary wood of the stem ; cb., cambium ; ph.*, phloém ; 
s.s., secretory sacs; pd., periderm, at outside of pericycle. X70. C.N. 
1640 (see pp. 709 and 712). 
Fig. 6. Transverse section through the leaf-trace bundle, /.t.*, of photograph 1. At 
this level the bundle has become double, and is without secondary tissues. 
The structure is exactly that of foliar bundles in Cycadee, e.g., Stangeria. 
Lettering as in fig. 5. x70. O.N. 1884 (see pp. 709 and 718). 
Fig. 7. Part of transverse section from the same specimen, to show cambium and 
phloém. «.*, secondary wood; *.,7., rays; cb., cambium ; ph.2, secondary 
phloém; ph., primary phloém ; s.s., secretory sacs in pericycle ; pd., peri- 
derm. X 70. C.N. 1640 (see p. 715). 
Fig. 74. Part of a tangential section through the secondary phloém. ph.?, strands of 
sieve-tubes and elongated parenchyma; 7., 7., phloém-rays; hy., branched 
- fungal hypha. X 70. From one of the new Oldham specimens (D. H. 8.) 
(see p. 716). 
