772 PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE - 
the remaining three are double; w., one of the six perimedullary strands of 
xylem. Between w. and /.t. a thin zone of secondary wood is seen. The 
external layer of cortex to the right is not evidently connected with this 
stem. X 11. CO.N. 1144p (see pp. 710 and 714). 
Photograph 3. Part of transverse section of a stem, showing the base of a petiole in 
connection with it. s¢., stem; pt., petiole. The petiole contains a double 
bundle, which is concentric. Plate 19, photograph 84, and Plate 23, fig. 10 
show other sections of the same specimen. x 8. O.N. 1980 (see p. 725). 
Photograph 4. Radial section of stem and petiole, showing the connection between 
them. d.c., Dictyoxylon cortex of stem ; pe., pericycle ; x.”, secondary wood ; 
p., pith; pt., petiole, cut off at this point; sc., axillary sclerotic band ; 
c., outer limit of cortex of petiole; /¢., leaf-trace bundle, entering petiole 
from stem. xX 34. C.N. 1982 (see p. 725). 
Photograph 5. Transverse section of a small secondary branch of a petiole. The 
outer cortex has the usual Dictyoxylon structure ; s.s., secretory sacs of the 
inner cortex; v.b., the concentric vascular bundle with V-shaped xylem 
completely surrounded by phloém. X about 35. O.N. 145 (see p. 728). 
Photograph 6. Transverse section of part of the lamina, cut through a number of 
leaflets just separating from one another. A part of one of the leaflets 
is displaced and seen in obliquely superficial view. x about 35. C.N. 
1885p (see p. 727). 
PLATE 19. 
Photograph 7. Vertical section of a leaflet. p.p., palisade parenchyma ; above this 
is the hypoderma, and then the epidermis; s.p., spongy parenchyma ; 
v.b., vascular bundle, in obliquely longitudinal section. On the under side 
of the leaf is an outgrowth, perhaps of the same nature as the cortical 
emergences. X about 70. C.N. 1196 (see p. 730). . 
Photograph 8. Part of a transverse section of a large stem, passing through the 
base of an adventitious root. ré., outer limit of cortex of root; cy., central 
cylinder of root, which has formed secondary wood; tr., tracheides con- 
necting the base of the root with the wood of the stem; «., remains of 
primary wood of stem; .*, its secondary wood ; pd., periderm ; d.c., Dicty- 
oxylon cortex; 1.t., large leaf-trace bundle. x about 12. O.N. 11448 
(see p. 733). 
Photograph 84. Another section of the same specimen as photograph 3, taken higher 
up. sé, stem; pt., petiole. Note the dark axillary band at the junction 
of the two. At 77. a root is seen in longitudinal section, passing out from 
the wood through the cortex. x 3. C.N. 1981 (see pp. 725 and 734). 
Photograph 9. Part of tangential section of the cortex of a large stem, showing base 
of adventitious root ; l.t., leaf-trace bundle of stem ; d.c., part of the Dicty- 
