444 MR. 8. G. SHATTOCK ON THE SCARS 
drying, aseries of deep longitudinal clefts is disclosed in the area 
through which disarticulation takes place. 
In Dammara robusta it is in this weakened zone that the plane 
of disarticulation lies. The process resembles in its details that 
by which deciduous leaves or other caducous organs are shed. 
If the base of the shed branch be examined by means of longi- 
tudinal sections, it will be seen that the cortical parenchyma is 
bounded at the detached surface by muriform sclerenchymatous 
cells in two or more rows, and on these are the remains of cork- 
cells; the same is seen in thelargely proportioned medulla, where 
there is a more distinct phellogen beneath the sclerenchyma; 
the bast parenchyma and cells of the medullary rays present 
similar changes. 
Longitudinal sections of the young scar on the stem show the 
cicatrix to be constituted by flattened cells of cork set in parallel 
tiers and a subjacent phellogen of similar form ; the fractured 
wood will be found covered in, in like manner, with cork and 
phellogen. 
In the older scars sclerenchyma may be found alternating 
with layers of cork: the sclerenchymatous cells are muriform 
like those of the cork amongst which they lie, and they are 
clearly produced periodically from the subjacent phellogen, their 
original connection with which is subsequently lost by a fresh 
formation of cork beneath them. 
From these appearances it may be gathered that the process 
of disartieulation is like that by which a leaf or other organ is 
shed; that is, the parenchymatous cells across the whole zone of 
articulation multiply by transverse division, a layer of cork 
resulting from the formation of this secondary meristem, and 
through the distal limits of this the solution of continuity occurs ; 
after this the slender connecting bond of wood is broken across 
by the weight of the branch or the first trivial violence, this 
completion of the process being aided, perhaps, by the tension 
made upon the wood in consequence of the cell-division of the 
surrounding parenchyma which occurs across its axis. It thus 
happens that the whole of the parenchymatous system of the 
stem is closed by cork before the branch is actually shed. 
The purpose served by such a systematic disarticulation is 
difficult to perceive. I have elsewhere suggested that in all such 
cases the process represents, or is an evolutionary relic of, & 
bygone means of asexual propagation. Certainly, in the case 
N: 
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