54 
Where the disease is serious it will be found necessary to apply 
a disinfectant to the tapped surfaces of every tree in the area. The 
infection takes place on the cut. That is on the thin bark most 
recently tapped. It is at this position then that the disinfectant 
must be applied. The most important questions are the frequency 
of application, the best disinfectant to use and the method most 
practicable in estate practice. From an article in the most recent 
.♦ Agricultural Bulletin I gather that in Sumatra it is found that the 
best results are obtained if the disinfectant is applied every day. 
From figures given in the article, by H. C. Pratt, to which I refer, 
it appears that this is the only satisfactory method. The disinfectant 
may be .20 per cent, carbolineum as used in Sumatra or its substitute 
20 per cent, brunolinum, 10 per cent. Xzal or a solution of sodium 
bisulphite and formalin. The last question — the most practicable 
method — ma} r well be left for the planter to decide. 
Burrs. 
These structures are too well-known to need any description. 
Rutgers and Arens considered that they are produced as a result of 
attacks of Phytophthora Faberi but there is no indication of the 
presence of a fungus of any kind within the tissue of a burr or 
nodule. 
Burrs are formed round a portion of a latex vessel as a result of 
alteration of the contents of a latex vessel. Whether that alteration 
be disintegration, decomposition or coagulation, cortical cells sur- 
rounding the latex vessel are stimulated to divide and form a 
cambium which cuts off wood cells on its inner side forming a core of 
wood tissue and bark cells on its outer side. The remains of 
the latex vessel are easily discovered when sections are examined 
microscopically. Similar nodules are produced as a result of latex 
oozing out of a tube or occupying spaces between the cells (intercellular 
spaces) or, occupying lesions in the cortex. Bryce divides these into 
three types, he distinguishes yet another type which 1 have not 
seen — namely, nodules which are formed round areas of cortex 
from which latex may be entirely absent. 
I have not been able to find any evidence whatever that this 
pathological condition has any connection, directly or indirectly, 
with the attack of any fungus disease or insect pest*. 
Bryce suggests that “ the tendency to suffer alteration in the 
latex vessel content appears to he confined to certain individual 
trees which have a predisposition to develop this condition.” 
I think myself that in a very large proportion of the number 
of burred trees the original central point (round which the burr 
develops) the factor which is the cause of the burr, is merely 
accidental, due to local coagulation or alteration of the latex within 
the tube or to the bursting of a tube allowing latex to occupy spaces 
where it is foreign. 
