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Systematic experiments on rubber-tapping were begun in 1908 on 
the old trees at Heneratgoda, then the only tappable trees under the 
control of the Botanic Gardens, and when it had been established that 
ree No. 2 at Heneratgoda steadily yielded an amount of rubber far 
in excess of any of the other trees in tapping, steps were taken to 
plant up an area with seed of that tree. There are now three acres 
of Hevea on the Experiment Station, Peradeniya, planted with that 
strain. The oldest (2 acres) was planted in 1912, with stumps one 
year old, and is not yet tappable. The intention at present is that 
when these trees are fit for tapping they will be tapped to determine 
which of them are good yielders ; the poor yielders will then be cut out, 
and the area reserved for seed. It is of course recognised that 
investigations on the subject of the inheritance of latex capacity 
may compel modifications of the scheme. 
yield has been recorded for every tapping since June, 1908, the trees 
aving been tapped continuously at regular intervals, varying in the 
different groups from one to seven days. And there is a large number 
of trees whose individual latex or rubber yield has been recorded for 
periods of one to two years. It is, therefore, scarcely correct to state 
that no attempt has been made to obtain reliable data as to the variation 
in yield of latex and rubber from individual trees. 
In 1912, an attempt was made to attack the problem from another 
side, viz., to determine whether the latex-yielding quality can be 
associated with any definite botanical character, and to what extent 
such characters are transmitted. 
On this subject, the individual planter generally has very definite 
views, but few agree with one another. In Ceylon, three types of 
bark are usually distinguished, smooth, moderately corky, and very 
corky. The smooth-barked tree is often regarded as a poor yielder, 
and this appears to be true, if the smooth exterior is associated with a 
yellowish and somewhat granular internal structure. But there is 
some evidence that the external appearance of the trees, in Ceylon, 
varies with the elevation of the plantation. Differences in the foliage 
have also been associated with latex yield, the small-leaved tree being 
regarded as a poorer yielder than the large-leaved form. On the other 
hand, the large-leaved tree appears to suffer more from the leaf-fall 
Caused by Phytophthora than the small-leaved, though it remains to 
be determined whether this is merely due to the fact that the loss of 
the same number of leaves makes a greater difference in the appearance 
of the tree in the former. There is also a tree with a dark glossy leaf 
which contrasts strongly with the normal leaf, a fact which may prove 
of service in the matter of disease resistance. With regard to the colour 
of the bark, it was stated in Ceylon some ten years ago that trees 
with a pink bark were poor yielders. On examination it was found 
that the pink external coloration was due to the presence of a red alga 
(Chroolepidae), which finds a better footing on smooth than on rough- 
barked trees. This accords with the late Dr. Huber’s statement that 
