442 MR. 8. G. SHATTOCK ON THE SCARS 
The foliage in Dammara robusta is confined to the neighbour- 
hood of the summit of the erect, undivided stem. The branches 
are given off in pseudo-whorls of five, with a slight upward 
obliquity or at a right angle, and they are usually confined in 
old individuals to the upper part of the tree. The branches are 
shed in succession from below during the upward growth of the 
tree, and the resulting scars persist on the stem, even to its 
lowest part. 
The general surface of the stem bears the sparsely scattered 
scars of fallen leaves, and the younger portions of the stem are 
strewn with lenticels. 
The scars, both branch and leaf, follow the general law of 
scar-growth ; that is, they grow commensurately with the part 
on which they are seated. 
The formation of the branch-scars in Dammara, as in the few 
other trees in which the branches are articulate, is altogether 
different from the scarring that occurs under ordinary conditions 
after the removal of a woody branch. 
Amongst the few trees which permit of branch-disarticulation 
may be mentioned, among Angiosperms, Populus tremula, some 
kinds of Willow, Quercus Robur, Antiaris toxicaria, *Castilloa 
elastica ; among Gymnosperms, an articulate disposition obtains 
in Gnetacee; and in Taxodium distichum the axes that bear 
leaves are deciduous (Sachs, Textbook, 2nd Engl. ed. p. 511). 
But in the vast majority of trees no provision for the disarticu- 
lation of branches exists. In very young branches, dying inter- 
nodes may be cleanly detached; but this occurs only before the 
permanent tissue of the wood is formed, and is effected by trans- 
verse subdivision of the elements of the whole of the ground 
tissue and procambium across the zone of demarcation, the middle 
cells of the zone becoming suberous. This process may readily 
be observed if a young branch of the Lime, for example, be divided 
through the distal end of an internode ; under these circumstances 
the whole of the internode is subsequently cleanly shed, sometimes 
after having undergone very little outward change; the process 
that ensues is strictly like that which accompanies the disarticu- 
lation of a leaf. 
With such an exception, the dead wood of a dead branch 
retains its connection with that of the parent stem until it is 
* See Note on the Disarticulation of Branches, by R. Irwin Lynch: Journ. 
Linn. Soe, vol. xvi. pp. 180-183. 
