ground and lined with dust, just as in the Serra do Ma- 
chado. The tree and the tapping method differ. The 
tree is scarcely more than a large bush, branched and 
spreading from a short trunk (Figure 2 A and Plate XL, 
C). It grows very rapidly and some one year old trees 
which were planted on fairly good soil in northwestern 
Pernambuco have been tapped. 
In Ceara the only native Piaui type trees are found 
along the southwestern margin of the state, and there 
are scarcely any plantings. ‘To tap the tree the roots are 
exposed, a hole is dug to receive the latex, lined with 
tabatinga (Plate XL, D), and a groove is cut into the 
root down to the wood. Every three or four days the 
coagulated rubber chapa is collected and a new cut made 
below the old one until it is difficult to reach into the 
hole with the tool. At this time the tree is abandoned 
for the year and, since the hole is rarely ever refilled, the 
uncut bark frequently dries and the tree dies. 
Well-prepared clean manisoba and mangabeira rubber 
can be used instead of Hevea in many small rubber in- 
dustries. To improve low grades like choro, which make 
up the bulk of the Ceara production, washing plants 
have been established in northeastern Brazil. In wash- 
ing, crude rubber is passed between two large rollers. 
These revolve at differing speeds and separate the rubber 
so that the streams of water which flow over the rollers 
can remove any dirt. If the washing is done well, the 
rubber leaves the rollers as a clean sheet of crépe which 
needs only to be dried before it can be utilized by the 
manufacturers. Washing low-grade rubber is difficult 
and expensive. For this reason, and because of the great 
diversity and variability of the Ceara rubber and the un- 
predictable fluctuations in production, it is unlikely that 
exportation will increase. Ceara rubbers cannot compete 
in either quality or cost with the Hevea produced on 
[ B14 ] 
