THE HEVEA RUBBER TREE IN THE AMAZON VALLEY 
31 
Table 5. — Comparison of restdts obtained by Akers (2, 
rubber trees with a gouge and with a m 
p. 84) by tapping Brazilian 
achadinho 
Number of— 
Quantity of latex (c. c.) 
Yfcld of 
dry rubber, 
Tool used 
Trees 
Tappings 
Total 
yield 
Per tree 
per day 
Per pound 
of dry 
rubber 
including 
lump and 
scrap 
(pounds) 
235 
57 
3,190 
798 
68,750 
32,000 
21.8 
40. 1 
886 
836 
77.52 
38 27 
Based on these data machadinho tapping for 180 days a year 
would give an average of 4.4 pounds per tree and gouge tapping 
8.6 pounds for the same period. To offset the decided improvement 
in yields Akers (2) found that experienced tappers could tap only 
60 to 70 trees a day and that after tapping for six months the cambium 
disease set in. 
Exact details of the methods used by Akers are lacking, but it is 
known that he brought experienced native tappers from the East. 
Whether these men were adequately controlled or not does not appear, 
but 60 to 70 trees seem a small task to the writer in comparison with 
the number of trees in a tapping field in the East, due allowance 
being made for the difference in conditions. However, at that time 
tapping systems were much more complicated and much more severe 
than at present, which may account for the small number of trees 
tapped as well as for the early and serious onset of disease. 
The writer laid out an estrada of 30 virgin trees on the Kio Ouro 
Preto, in Matto Grosso, Brazil (see fig. 3), and tapped them for a 
few days, using one cut on one- third the circumference. All tapping 
was done to the wood in order to give results comparable to those of 
the ax, which penetrates to the wood. 
The cuts were opened to the wood on one day; the next day tapping 
was begun. The scrap from the cut of the day before was put into 
the cup with the latex yield of each day. This introduced a small 
error in the quantity of latex, since the scrap rubber is somewhat less 
in volume than the latex from which it comes. Where the yield is 
very small most of the rubber is coagulated on the cut as scrap, and 
this makes the measurement of the latex merely an approximation. 
Tree No. 17 in Table 6 is an example of such a condition. With the 
average tree the errors are small and over long periods are practically 
negligible, so that this proceeding offers as satisfactory a means as 
has been found of obtaining the total daily yield of a tree. 
Time was available for only four consecutive tappings, the results 
of which are given in full in Table 6. It is unfortunate that the trees 
could not have been tapped long enough for the wound response to 
become fully established, so that the trees might have shown their 
full yielding power. A considerably larger yield might have been 
expected later, for five days is not long enough for the full response to 
tapping to be shown; in fact, some trees do not yield to their full 
capacity for at least a month after tapping is begun. 
The results were enough to show that tapping with a knife accord- 
ing to the plantation method will very likely be successful under 
proper conditions. The yields compare favorably with those of good 
areas of rubber on oriental plantations, though the latter are, of course, 
for trees younger than the Matto Grosso trees (18, 20). 
