129 
Anomalous I^orms of Dicotyledonous Stems. 
tating condition at its apex. Each scar presented on its roundish 
disc the almost perfect circle of vascular bundles of the fallen 
leaf; above the scar was a dried bud, and below it a strong, 
blunt ridge ran downward on the stem. On each side of the 
cicatrix was a little semicircular scar indicating the articulation 
of the fallen stipules, and from each of these lateral scars an 
acute ridge originated which became united with a similar one 
coming down from the leaf next above. On the examination of 
the living leaves it was perceived that the vascular bundles of the 
petiole formed the central woody mass, and those of the wing of 
the petiole and of the stipules, the lateral bodies. These were 
quite isolated just below the node ; but in another twig which 
was examined, either two or the whole of them w^ere always 
united to the central mass, and this was particularly the case in a 
twig which had a roundish instead of the usual triangular form. 
So that this anomalous structure of the wood of Sapindacea has 
its oiigin at the earliest stage, and is connected with the forma- 
tion of leaves rather than of branches, and depends upon a pecu- 
liar tendency of the vascular bundles to develope independently 
of each other, round several centres, which tendency however 
they occasionally lose and subsequently blend with the central 
mass. 
The structure of the wood of the Malpighiaceous Lianes agrees 
to a certain extent in appearance with that of the Sapindacece, 
and here it is evident that the lateral bodies do not belong to the 
hber. But according to A. de Jussieu the lateral bodies show no 
disposition to arrangement of their fibrous tubes and vessels 
around a pith, as occurs in the Sapindacece. He has also shown 
that the wood lying immediately around the central pith is very 
regularly formed, and has narrower and straighter medullary 
rays than the layers subsequently produced; while in the Sapin- 
dacecE the separation of the lateral from the central masses is evi- 
dent in the very earliest stages of the formation of the wood. 
In the same memoir Jussieu has mentioned several climbing 
dicotyledons of very different families, where the masses of wood 
have a tendency to become separated from eaeh other j to these 
may be added the climbing species of Begonia. Those species of 
Begoniaj\^ an upright stem have the wood symmetrically formed 
but m for example, B. hirtella, the wood on the side of the stem 
next the wall on which the plant grows is scarcely half so thick as 
upon the other side which has been exposed to no pressure ; on 
this side the wedges of wood are much expanded and quite un- 
symmetrical, being separated from each by medullary rays which 
equal them in breadth. 
Lastly may be mentioned some peculiarities in the wood of 
certain climbing Bignoniacea, figures of which are given by Lind- 
Ann.^^ Mag. N. Hist, Ser. 2. VoU. 9 
