698 PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE 
pith (P) of the root has been perforated by a Stigmarian rootlet. Eight strands 
of primary xylem are shown (as at X), around the pith; some are missing. The 
secondary wood (X?) of the root is continuous with that of the stem on which 
it is borne. C.N. 1352. x about 10. (See p. 685.) 
Photograph 2. Part of another tangential section from the same stem. One of the 
large infranodal rays or “lenticular organs” is shown (1.R.). Above this, 
and to the right, is the transverse section of an outgoing foliar bundle 
(L.T.). C.N. 1353. xX about 16. (See p. 685.) 
Photograph 3. Transverse section of a large corticated root. (For cortex and phloém, 
see Plate 17, figs. 10 and 11.) Pith (P) perforated by a Stigmarian rootlet. 
Fourteen primary xylem-strands are shown (asat X); some are missing. The 
secondary wood (X*) has a maximum thickness of about 50cells. C.N. 1891. 
xX about 10. (See p. 687.) 
Photograph 4. Transverse section of a corticated root. Pith (P) solid, surrounded by 
about twelve strands of primary xylem. Secondary wood (X*) only about three 
cells thick. Cortex (C—C) lacunar, with very numerous trabecule. Intrala- 
cunar cells (? thylosis) are seen. Possibly a different species from the other 
specimens. O.N. 18914. x about 12. (See p. 690.) 
Photograph 5. Transverse section of a tetrarch rootlet, without pith ; CY, centre of 
cylinder. Formation of secondary wood has begun. The double endodermis 
(the inner layer of which is thin-walled) can be recognized (HN). The trabecule 
of the lacunar cortical zone show thylosis. The cortex (C) is limited externally 
by a thick-walled, epidermoidal layer (HP) C.N. 18904. X about25. (See 
p. 691.) 
Photograph 6. Transverse section of a pentarch or hexarch root (decorticated), 
showing the bases of two branches. There is a small solid pith (P). Five 
primary xylem-strands (X) are plain. Opposite two of them are the branches 
(BR), which show little or no pith. Secondary wood of branches continuous 
with that of principal root. C.N. 18924. »X 22. (See p. 695). 
Photograph 7. Part of transverse section of a root, showing the base of a branch (BR). 
The root had sixteen strands of primary xylem (X), of which four are shown, 
with part of the pith (P). The base of the branch-root is separated from the 
primary xylem, opposite which it arises, by about fifteen layers of secondary 
wood ; X*, limit between the two layers of secondary wood. O.N. 1323. X 22. 
(See p. 695). 
