56 
vertical and to develop spirally. A ridge is formed on the upper 
side of the vine and there is a corresponding stagnation of growth 
on the under side. If the vine is small it may be completely over- 
grown in parts, giving the tree a spirally fluted appearance. 
Clinging vines were observed in a few instances to interfere seri- 
ously with the development of the crowns of young Hevea, causing 
suppression. On neglected plantations and in the jungle these condi- 
tions may be expected. 
ORCHIDS AND AROIDS 
Perched upon the branches or attached to the trunk of Hevea 
various species of epiphytic orchids, aroids, and other flowering 
plants were occasionaly observed. Xo damage resulting from such 
growths was encountered. The compact root masses of many of 
these plants harbored large numbers of ants. The white ants oc- 
casionally extend their runs to these clumps, and for this reason the 
plants should be destroyed on all well-regulated estates. 
PHYSIOLOGICAL DISTURBANCES AND ABNORMALITIES 
BROWN-BAST 
The brown-bast disease, which is the cause of much damage in 
eastern rubber estates, concerning which an extensive literature has 
developed, occurs in the American Tropics, but apparently in a 
mild form. 
Dr. Carl D. La Rue discovered near Para a tree which exhibited 
all the symptoms usually attributed to this disease, and the writer 
located several others in the same locality. These trees, which aver- 
aged about 14 inches in breast-high diameter, had been excessively 
tapped by the usual method, whereby a small ax is driven through 
the cortex into the wood. The wounds in healing had produced 
numerous callous formations, a result which usually follows this 
mode of tapping. It was noted that the cortex around some of the 
unhealed wounds did not produce latex, appeared watery, and was 
of a yellowish gray color intermixed with brownish spots. Since 
these symptoms indicated the presence of brown-bast a close ex- 
amination of several trees was made. The trees had all been tapped 
in the manner described above, and all had produced numerous 
small nodule and callous formations. These formations in some cases 
were unusually large and conspicuously roughened. The small 
nodules usually were lightly attached and could be removed with 
the fingers. Out of five trees discovered with brown-bast symptoms 
a considerable variation in the appearance and location of the dis- 
colored areas in the cortex was noted. A peculiar feature was the 
breaking up of the surface bark in the form of brittle scales. When 
shaved down smooth with the bark their location and outline were 
well defined (PI. XXX, C). These scales with their margins de- 
fined and slightly raised w T ere firmly attached in the center. When 
pried off with a knife a greenish yellow watery appearing surface 
was exposed. A cut on this surface appeared dry without a flow 
of latex. Owing to the irregularities of the bark due to callous 
formations these scales were never more than 2 or 3 inches in diam- 
