288 
For that purpose a few trees were, in that year, worked with a 
larger number of incisions than was the case in the previous year. 
Tree No. 3 yielded, at the first tapping in the first year from a 
surface of 2*6 M2 and a total length of the incisions of 104 cm., 41 1 
grammes of rubber. 
At the second tapping in November of the same year, these figures 
were, respectively, as follows, 2.6 M 2 ; 320 c. m. and 998 grammes: — 
and at the third tapping in the following year, 3.27 M 2 ; 740 c.ir,, 
and 1332 grammes. 
Reducing the yields to M 2 surface, then we get with 104, 32 °> 
and 740 cm. lengths of. incisions, respectively, 158, 384 and 407 
grammes. With a proportion of lengths of incisions of 1 : 3 : 7; the 
ratio of the yield is as 1 : 2: 4: 2'6. 
These last are not in proportion to the number of incisions. The 
most unfavourable is the case in which the number of incisions is 
taken 7 times greater. 
The figures are readily comparable, because the tap periods were 
nearly equally moist, only in the last case it was cut 10 times instead 
of 11 times, as had been done in the other instances. 
It is a mere chance if the temperature of the one year is the same 
during tapping season as that of the following year. 
Small variations do not harm, but large differences in the number 
of rainy days and the quantity of fallen rain influence the yield of 
rubber to a high degree as we shall be able to point out with figures 
of our experiments of tapping. 
From the above experiments we see that an increase of the num- 
ber of incisions furthers the yield of rubber, but not in the same 
proportion. 
As the incisions always cause more'or less' harm to the tree, we 
must not make this number greater than is necessary to get nearly 
the biggest possible yield. o 
According to the above experiments, an increase of 23 grammes 
of rubber per square metre of tapped surface is only obtained after 
more than doubling the number of incisions. 
In the second year, the trees were tapped as high as possible, 
usually to the point where the branches begin to appear. In order 
to be able to tap at that height, ladders had to be used. 
In this way, however, much time was wasted in the collecting. 
We then came to the conclusion that it is of no advantage to tap 
the trees to a height which the native tappers could reach with 
ease without having to make use of ladders. 
From former experiments made, we knew already that the lower 
part of the trunk gave th.e bigger yield. 
We shall see from experiments of the second and third year that 
the lower tapping is more advantageous. 
