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BEYCE : 
In two later Bulletins (17 and 18) Kuijper considers that 
the formation of nodules points to the existence in Hevea of a 
strong tendency to produce abnormal growths, this tendency 
being accentuated by tapping or otherwise wounding the tree. 
Normally the cortex is subjected to internal pressure owing 
to the growth in thickness of the wood of the stem. In 
nodular cortex there is, in addition, the pressure owing to the 
growth of the nodules. This must have a disturbing effect 
on the tender cambium of the main stem, and probably this 
disturbance is manifested in the uneven, pitted, and ridged 
surface of the wood of the main stem under areas of nodular 
cortex. He contends that the pricker has no effect in inducing 
nodule formation in normal trees. 
Rutgers and Arens (28), in a paper printed for the Rubber 
Exhibition at Batavia (1914), discuss nodules as the result of 
an attack of canker (Phytophthora Faberi Maubl.). The fungus 
kills small points and lines of cortical tissue, and these areas of 
dead cells act as an irritant on the surrounding healthy cells, 
which then divide to form a cambium, and so nodule formation 
is begun. Rutgers, after a short visit, claimed to have found 
Hevea canker caused by Phytophthora Faberi in the Federated 
Malay States ; but this cannot be held to be conclusive, as 
it is not borne out by the work of Federated Malay States 
mycologists. Cf. Brooks (8). The presence of nodules in 
the Federated Malay States is well known ; thus, under the 
circumstances, canker cannot be satisfactorily considered as 
the cause of nodule formation. 
Richards and Sutcliffe, in the Straits Settlements, in a 
pamphlet (24) issued in 1914, consider the question of the 
formation of nodules. They accept Bateson’s theory of the 
development of nodules on old leaf scars, the stimulus to 
nodule formation being the irritation set up by the coagulation 
or decomposition of the latex in the fragments of latex vessels 
remaining from old leaf traces. They apply the theory to the 
formation only of pea -like nodules. The plate and sheet 
nodules are formed round the outer latex vessels, as they are 
gradually pushed outwards and broken up by the new cortex 
which is continually being formed by the cambium ; the 
stimulus to nodule formation is again the irritation set up by 
