COMPARATIVE ANATOMY OF THE CYCADACEZ. 457 
EXPLANATION OF PLATE 20. 
The following are the abbreviations used :—ct=cotyledon ; pl=plumule ; 
sl=scale-leaf ; /—leaf ; pr-protoxylem ; z! =centripetal xylem ; z?— centri- 
fugal xylem; z—xylem; ph— phloem ; c—cambium ; ac— anomalous cambium ; 
es—cortical strand ; 7— radiele. 
Fig. 1. 
Fig. 7. 
15. 
16. 
. Transverse section of a concentric bundle 
Cycas revoluta, Thunb. 
Young seedling with the cotyledons embedded in the megasporangium, 
the outer coat of which is partly removed. Nat. size. 
. Another view of the same. Nat. size. 
A somewhat older seedling with the cotyledons embedded in the 
megasporangium, two scale-leaves enclusing the plumule, and an 
elongated, branched radicle. Nat. size. 
. The same with the megasporangium entirely removed, leaving the 
fleshy cotyledons exposed. Nat. size. 
. Transverse section of a portion of the root-stele from the hypocotyl of 
a young seedling, showing one of the small extra-fascicular con- 
centric strands. X45. 
. Transverse section of a cauline cortical strand from the stem of one of 
the older seedlings. 
Cycas media, R. Br. 
Diagram of a transverse section of a cauline cortical strand at the 
periphery of the stem. 
. Transverse section of a portion of a cauline cortical strand. X 30. 
. Two tracheides from the central region of a cauline cortical strand. 
x 130. 
Stangeria paradoxa, T. Moore. 
. Seedling, with the cotyledons removed from the megaspcrangium 
Nat. size. 
. The same, bearing the first foliage-leaf and the cotyledons embedded in 
the megasporangium. Nat. size. 
. Surface view of young foliage-leaf showing the four pinne. Nat. size. 
. Transverse section of a collateral bundle from the upper part of the 
lamina of the cotyledon. 
from the upper part of 
the stalk of a cotyledon where it is still coherent with the stalk of 
the other cotyledon. X390. 
Longitudinal section of the same. x 390. 
Transverse section of a collateral bundle fr 
stalk of a cotyledon where it becomes a separate organ. 
om the lower part of the 
x 390. 
