RUBBER (HEVEA) DISEASES / 
On dead roots of Calophyllum sp. (Guttiferae). 
On dead wood of jarana (Chytrvma sp. ; Lecytbidaceae). 
On dead roots of samauma (Ceiba pentandru ; Bonibacaceae). 
On living stump of cacao (Sterculiaceae). 
On dead stub of Cocos (Palmaceae). 
On dead wood of CalcycophyUum sp. (Rubiaceae). 
On dead log of Triplaris sp. (Polygonacere). 
On living stump of Ficus sp. (Urticacese). 
On living roots of jack (Urticacese). 
The above-named hosts represent a wide range of families and 
genera. There was no evidence of a marked proclivity of the fun- 
gus to adapt itself to any particular host. In most cases the hosts 
were of species which may be said to have soft wood, but one col- 
lection was made on the roots of an old log of C alcycophyllurn 
spruceana, one of the hardest woods in the Amazon Valley. 
In all four cases of the fungus on Hevea the lateral roots were 
attacked. In one case both the laterals and taproot were attacked, 
resulting in the recent overthrow of the tree by the wind. It would 
appear that the fungus is of economic importance in the rubber- 
producing regions of tropical America and will result in financial 
loss if protective measures are not introduced along with the estab- 
lishment of plantations. This statement, however, should be sub- 
stantiated by further investigations on the parasitism of the Ameri- 
can plant. 
The external symptoms of the attack on the three standing trees 
were the production of sporophores within root crotches. These 
appeared on one side of the trees only. The trees exhibited eccen- 
tric development on the uninfected side, causing concavities to the 
right and left. This is in accord with the effects of root fungi on 
timber trees in the Temperate Zone. The fluted condition of the 
base may indicate that the taproot has been destroyed, the increas- 
ing girth then being more pronounced over the main lateral roots. 
The same phenomena were observed in the case of other forest trees 
of the valley when attacked by root fungi or where the laterals were 
otherwise destroyed. The foliage on the three trees was abnormally 
thin and in all stages of development; but, being at a season when 
defoliation was common, the condition had no significance. The 
failure of many small twigs of the last few nodes to produce leaves 
in the upper crown apparently reflected the health status of the trees. 
The internal symptom of the fungus is the presence of a soft watery 
decay. The diseased wood in the last stages of decay may be 
squeezed in the hand into a shapeless mass. The bark of the infected 
roots may exhibit a darker brown color than normal and when 
removed may exhibit white, yellowish, or reddish strands of my- 
celium on the under surface or embedded in the decayed wood (PL 
III, A). In some cases there was a development of a mycelial net- 
work of strands on the exterior of roots, as has been reported for the 
fungus in the East (PI. Ill, A). This soft, spongy, watery decay 
was found in the roots of a Hevea tree that had been injured by 
fire. The rot when rolled up for a time in a paper bag produced 
the reddish yellow strandlike mycelial growth which was probably 
indicative of the presence of Polyporus lignosus. 
The fructifications of the fungus on dead stumps (PI. II. B) 
or standing dead trees rarely were found more than a foot above the 
ground. Usually originating in the hollow root crotches the fruit- 
