446 MB. 8. G. SHATTOCK ON THE SCARS 
primarily related: the bundles are ruptured by the tension of 
the general cambium-growth ; and in microscopical sections the 
two portions are easily recognizable in these two situations, 
beneath the cork of the scar, and buried in the deepest part of 
the wood; and this is true however widely separated the two 
portions may be by the annual additions of wood to the general 
surface of the branch *. Inthe leaf-scar still another rupture of 
the fibro-vascular bundles is to be observed ; the addition to the 
deeper part of the cork of the scar effects a rupture of the bundles 
in this situation ; and remains of these are to be detected in the 
boss of cork which marks their situation in the scar separated by 
the deeper and subsequently formed layers of cork from the ends 
of the bundles in the subjacent ground-tissue. 
Each yearly addition of wood to the stem in the case of 
the branch-scars of Dammara serves to increase by so much 
further the interval between the woody relies of the shed branch 
in the parenchyma of the scar and the central medulla. In 
longitudinal sections, however, the point of origin of the shed 
branch from the deepest part of the wood remains easily dis- 
cernible, however great the additions made to the general surface 
of the wood may have been. In the later history of the scar, 
wood is formed in the central parench yma; that is, in what before 
disarticulation was continuous with the medulla of the branch. 
This doubtless occurs, as in similar cases, by the formation of 
secondary wood-forming meristem from the indifferent parenchyma 
or ground-tissue. A complete screen of wood is before long 
formed. This increases in thickness commensurately with the 
stem, although the wood produced from the medullary parenchyma 
of the scar is not in the arrangement of its elements uniform 
with that around, but forms an almost distinct system. In lon- 
gitudinal sections of old scars this wood appears as a cylindrical 
process or core, connected, it may be, but little with the general 
wood around, the cells and vessels of which arch round on 
either of its sides. On removing the cortex from a scar of old 
date, a deep central fossa is exposed, the bottom of which corre- 
sponds with this woody core. The depression in the wood 18 
filled in by a corresponding process of cortical parenchyma and 
* The bast-fibres passing to the scar, however, are not involved in the rup- 
ture, since the general bast is displaced outwards equally with that of the scar 
in the subsequent process of growth. 
C nn 
