1 he mycelium takes the form of light brown threads when young 
and 'becomes later expanded over the surface of the root in the form 
of sheets, and collected here and there into nodules. The sheets of 
mycelium are dark in colour on the surface, and white or light brown 
beneath. 
Jn Ceylon the progress of the disease is said to be very slow, and 
observations which have been made in this country up to the present 
confirm this. In some cases where the tap root was attacked, it has 
been found that adventitious roots have arisen, and having grown 
vertically downwards have taken the place of the tap root— a further 
indication of the slow progress of the disease. At each centre of 
infection one or two trees only have been found to be diseased, and 
each case has been found to be the result of a separate infection. 
i he mycelium appears to be incapable of spreading independently 
through the soil, and infection can, therefore, only occur by the Con- 
tact of a diseased with a healthy root. The growth of the mycelium 
is, however, so slow that the attacked tree is dead some time 
before the fungus has spread to the adjacent trees. Where two ad- 
jacent trees are attacked simultaneously, each has become infected 
separately from one or more jungle stumps. If the dead tree be left 
standing for some time the disease may spread to the adjacent trees 
To illustrate the slow progress of the disease Mr. Petch, Mycologist*, 
Royal Botanic Gardens, Ceylon, cites the following instance : — “ Hevea 
was planted, 14 feet apart, in single line round the boundary of an old- 
established Cacao estate. When the trees were eight vears old, one of 
them died, from brown root disease as was subsequently discovered. 
The tree was left standing and allowed to decay. Two years later 
the next tree in the line died and was likewise left to decay. After a 
lurther two years had elapsed, the next tree in the same direction 
along the line tailed to recover after wintering, and was evidently 
flying; and an examination of this tree and the two old decaying 
stumps proved that they had all been killed by brown root disease.” 
In Samoa and in West Africa, the disease appears to be more 
serious than either in Ceylon or in this country. When reported at 
Kew from West Africa the disease was said to spread somewhat 
rapidly, and in Samoa it has been said to cause considerable iniury to 
breadfruit ( Artocarpus inci&i.) 
The youngest age of an attacked tree which has been recorded in 
this country is three 3'ears. 
Spread. 
From what is known of the fungus it is unquestionably a jungle 
product, and, from the long list of cultivated plants which it attacks, 
one might infer that in the jungle it does not confine itself to any 
small number of hosts. 
