220 
working independently in Java, carried on the work much 
further, and his conclusions supported those of Petch as to the 
cause of bark canker of Hevea brasiliensis. 
Investigations in Java by Rutgers. 
Rutgers investigated bark canker of Hevea brasiliensis in great 
detail and contr eka Md aaek information ae nae the 
place on the Ree eut, and if the Peis enters the renewing 
bark, ‘ Streepjeskanker’ or Lin e-canker (Form A) is the result; 
if the untapped bark is affected ‘Vlekkanker’ or Spot-canker 
Rutgers ae his observations on Spot-canker in detail 
B, C, D (loc. cit.) : — 
Roe ae or as :—The second acute form of canker is the 
ark is removed we , not the green colour of the outer living 
bark (phellogen), but a black i re and below it a damp 
dirty-red canker spot is found sharply defined from the surround- 
ing ‘healthy yellow bark. If these diseased spots are not treated 
in time they reach a great size and kill the bark a to the 
wood, while in bad cases the whole tree may be rin he 
diseased spots yield no latex when cut, though the healthy 
surrounding tissue does sometimes yield an unusual quantity. 
(C). Sometimes the red canker spots described under (B) have 
only a limited spread, but a discoloration is found in the inner 
‘ 
bark close to the cambium his form is usually less striking 
than Form (B) but the infection proceeds further. It appears 
on the cut in dirty brown rey lines and sine sometimes also 
‘oF If the cases Sinhala in (C) are not treated they may 
lead to very noticeable swellings, i.e., ‘‘ Burred trees.”’ The 
grey lines and spots are dead cells or latex receptacles with 
coagulated latex, in the midst of living bark tissue. Under 
certain circumstances not yet known these dead cells cause the 
times appears in small round bullets like the ‘peas’? found on 
healthy trees; sometimes from the beginning large plates of wood 
are formed. these wood formations are not treate in time 
they continue to increase -in size and thickness and may 
develop alarming dimensions. This is the origin of the trees 
