30 
BULLETIN 1422, U. S. DEPARTMENT OF AGRICULTURE 
The Jebong knife and the gouge which are used for tapping in the 
Orient are absolutely useless on trees which have been tapped with 
the machadinho, on account of the huge excrescences which develop 
on the trunk and over which tapping can not be done without con- 
stantly penetrating to the wood. Possibly after a few years' rest the 
trunks of such trees would become sufficiently regular to allow tap- 
ping, though still with much more wounding than would ever be neces- 
sary in a normal plantation. 
Knife tapping over one-third or even one-fourth the circumference 
of the trees opens the vessels of a much larger part of the trunk than 
does the number of ax cuts now usually made by the seringueiro. 
This is shown in Table 4. 
Table 4. 
-Lengths of cuts made in tapping rubber trees by different methods, the 
' data being obtained from various estradas 
Machadinho tapping 
Knife tapping 
Total 
length of 
cut (cm.) 
Number of cuts per tree 
Total length of cut 
(cm.) 
Number of cuts per tree 
One-third 
circum- 
ference 
One- 
fourth 
circum- 
ference 
1 
8 
24 
16 
16 
8 
40 
24 
40 
32 
48 
24 
32 
32 
32 
40 
1 
26 
44 
32 
34 
25 
78 
41 
108 
106 
118 
76 
101 
106 
103 
115 
20 
3 
1 
33 
2 
1 
28 
2 
1 
1 
1 
26 
19 
5 . 
1 
58 
3 : 
1 
31 
5 
4. 
1 
1 . 
81 
79 
6 
1 
89 
3 
1 
57 
4. 
1 
75 
4.. 
1 
80 
4 
1... 
77 
5. 
1 
87 
The length of cuts made by the knife is at least twice that of the 
total length of cuts made by the machadinho in the trees shown, 
which are typical ones from various estradas. The greater length of 
the cuts should give greater yields, but this is to some extent counter- 
balanced by the fact that the ax cuts extend to the wood, while the 
usual tapping with the knife goes only to within 1.5 millimeters of the 
cambium, as has been determined by the writer (18). 
Akers (1, 2) attempted to introduce the oriental systems of tapping 
into Brazil and caused a number of experiments to be made in various 
places. Unfortunately, the result of these experiments has been 
to confirm everybody in the belief that such methods are not adaptable 
to South American conditions. The report of his experiments has 
traveled throughout the rubber country, and everybody thinks, 
whether rightly or not, that all the trees tapped by the Akers com- 
mission died at once. - 
Akers himself concluded that oriental methods could not be used 
in Brazil on account of bark-rot and also on account of the high 
labor cost. In experiments performed on an estrada near Abuna, 
Matto Grosso, Brazil, he secured the results shown in Table 5. 
