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BRYCE : 
vessels, and consequent formation of nodules ; these are (1) 
leaf-fall, (2) disease, (3) wounds. In the case of disease, 
healthy patches of cortex may be isolated by the diseased 
tissue, and in these patches nodules are found. Exhaustive 
tapping is considered as a further cause of the development 
of nodules. His conception of root pressure is faulty, and 
the assumption of a diurnal vertical movement of the latex in 
the latex vessel under the influence of this root pressure is 
unwarranted on the evidence led. The evidence cited applies 
normally to every Hevea tree ; we would therefore, on this 
theory, expect to And nodules occurring as the normal 
condition ; actually they are found only on a very small 
percentage of trees. 
In the present Paper a clear distinction is drawn between 
“ nodules ” and “ globular shoots.” By “ nodules ” is under- 
stood the woody structures formed round altered latex vessels. 
“ Globular shoots ” are the spherical woody structures formed 
as the result of the slow growth of dormant buds, which have 
lost their vascular connection with the stem. These latter 
comprise the great majority of the structures found in 
untapped trees. 
Macroscopic Appearance. 
Stems with large nodular growths are externally strongly 
gnarled and warted. The area of stem affected may range 
from quite a small patch of a few inches across up to an area 
comprising the whole circumference of the stem to a height 
of 5 or 6 feet. The surface of the bark is covered with warts 
and protuberances ; deep cracks and Assures abound, from 
which latex often of a yellow or chrome colour oozes out and 
coagulates. 
In the early stages the nodules are little spherical or 
elongated bodies of 1 or 2 millimetres diameter, which can 
only be detected with difficulty. The first outward indica- 
tions are a slight raising and cracking of the bark. The 
nodules at this stage are like little “ peas ” of wood lying in 
the cortex, from which they can easily be “ shelled out ” with 
a penknife. The nodule separates from the cortex along the 
line of the nodule cambium ; between this and the stem 
cambium there is a layer of normal cortex. 
