STEMS, LEAVES, AND BUDS. 
43 
as much from the layer of wood, as in the nodes of the larger 
grasses, for instance, of Zea, Mays, and Saccharum offici- 
narum (Icon. An. Bot. fig. 1, t. 2, figs. 5, 6) ; fig. 5 exhibits 
something of this entangling in the magnified degree of 82 i. d. 
The iDwer spiroids descend straight down, the upper make a 
curve towards the interior, and between them there is cellular 
tissue. A horizontal cellular tissue is also seen at g, like 
a medullary sheath, which has given rise to the conjecture, 
that the wood is produced here also from the cellular tissue, 
and that, by growing from the interior to the exterior, it 
compresses the cellular tissue. Every thing is the same here 
as in the Monocotyledons, the compound layers of wood, 
alone, are calculated to create doubts. We ought to consider, 
however, that the entire cauloma of the Cycadem is to be 
considered as a lengthened monocotyledonous node. In the 
second volume of the Icon. Anat. Bot. t. ix. fig. I, I have 
caused a longitudinal incision of Zamia Altensteinii to be 
represented. The same kind of woody bundles, exhibiting a 
similar net as those possessed by Encephalartos, are also 
seen here. The spiral vessels of these bundles are repre- 
sented, in a magnified degree, in fig. 2. The circular layer of 
woody bundles is not so developed in these Gycadeoe as in 
Encephalartos, Fr. Gull. 
The leaves of the Gycadeoe have a peculiar character. 
They are jointed at the base, that is, they are seated upon a 
stalk, from which they fall off, as soon as the stem or they 
themselves begin to wither This stalk is of the same thick- 
ness as the lower part of the leaf, and exhibits, externally, 
interruptions towards the end where it is joined to the leaf, 
which, however, do not extend themselves into the interior. 
Other leaf-like parts are found beneath these leaves, one such 
part being under each leaf. See Icon. Sel. part ii. t, 1, s. 1, 2, 
and t. 2, s. 1, 2. If now we should assume, as a general law, 
that the branches issue forth from the axil of a leaf, and are, 
therefore, supported by leaves, that two genuine leaves are 
never seated one under another, or that one leaf is never 
situated in the axil of another leaf, we should, in such case, 
have to consider those parts of the Gycadem which are 
435 
