plains barely cuts to the wood, but opens more latex 
vessels. By substituting the machete for the hatchet or 
inducing the producers to use wider-bladed hatchets, it 
was possible to decrease the damage to the trees, preserve 
a bark surface satisfactory for retapping, and at the same 
time increase the yield of rubber with no extra labor. A 
modified Amazonas knife to cut a deep groove was un- 
satisfactory because cuts which were too close together 
left the bark between them dry and dying, a ready shel- 
ter for termites. 
In the same area, the Serras of Maranguape and Ba- 
turité, a type of manisoba tree occurs which yields 
practically no latex. This is called manisoba brava, wild 
manisoba (Figure 2 D). There is a complete series of 
intergrades between the best yielding manisoba and the 
driest of these wild trees. It is difficult to say whether 
there are two intergrading species or one variable species. 
Frequently one can distinguish the extremes by their 
bark, which is gray and thickened in the rubber-yielder, 
and reddish or silvery (usually smooth and thin) in the 
wild type. The natives believe that by hacking them 
regularly, it is possible to stimulate or ‘‘tame’” (@mansar) 
some of the wild trees so they will produce latex (Plate 
XLI, C). If the latex does not flow after three or four 
weeks of this treatment, the trees are abandoned. The 
basis for this belief in ‘‘taming”’ is a phenomenon known 
as wound-response. In response to the stimulation of 
tapping, manisoba and Hevea both increase their yield 
slowly for about three weeks when they reach a maxi- 
mum at which they remain unless overtapped or injured. 
West of the Serra de Maranguape the trees resemble 
the brava type, although in damp places they still yield 
enough latex for cup-tapping. Trees of the drier places 
are cut and hacked with the machete so the latex flows 
over the trunk (Figure 2 C) and coagulates and dries in 
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