53 
Dr. Trimen, Superintendent of the Botanic Gardens of Ceylon, 
and these results are as follows: — 
5 year old mean yield of 77 trees : 2. 3 oz. per tree. 
6 „ 61 ,, 2.0 „ 
8 ,, ,, 6t ,, 1 . S „ 
12 ,, 61 „ 4 - 3 <■ .» . 
My chief reason for quoting Dr. TrIMEN’S figures is merely to 
call renewed attention to the absolute necessity of carefully ascer- 
taining the yield of the Castilloa tree iu any district in which it is 
intended to cultivate it. Dr. TRIMEN'S figures cannot be looked 
upon as representing the yield ot Castilloa elastica anywhere but 
in Ceylon or Java, but they convey a vivid idea as to the extra- 
ordinary degree to which different conditions of soil and climate 
may affect the yield of rubber. 
My own results obtained at Las Cascadas are as follows 
Age of tree. Yield of latex. % of rubber in latex. Yield of rubber. 
6 1 tb. 13 oz. 26 7*5 02 
7 2 „ 5 „ 26 9-6 „ 
AS 3 „ r 29 14*2 „ 
ri 5 » 3 3i ^ 9-1 »i 
As the trees can with perfect safety be tapped twice yearly, the 
annual rubber yield mav be taken double that in the last column 
of the above table. These yields as regards the trees of 8 and n 
years of age respectively, are the means of a number of fully de- 
veloped trees of the two respective ages. The yields of the younger 
trees above given were obtained on tapping two representative 
trees of the respective ages, and taking the mean of the yield ob- 
tained as the real yield, 1 consider the above figures rather below 
than above the mark. But it is nevertheless well worth pointing 
out that as even Castilloa trees of the same age are apt to exhibit 
astonishing differences in their development it is only to be expected 
that thev do so likewise as regards the quantity of rubber they 
produce, and it is perhaps not and altogether sate procedure to 
ascertain the aggregate yield of a rubber plantation by simply mul- 
tiplying the number of trees on the plantation with the however 
carefully ascertained yield of a limited number of trees. It is fur- 
ther my opinion that the method of planting and rearing young 
rubber plantations, always speaking of Castilloa elastica, is a matter 
deserving of much closer and more careful study than it has so far 
obtained. The method of simply planting out in a forest clearing 
so many seeds, or seedlings, at so many feet distance, I consider 
altogether inadequate. With this highly important matter I propose 
to deal at some future occasion. 
The question regarding the best method of tapping the rubber 
trees is one which just now is engaging the attention of most of 
those occupied in rubber planting. Of course, there are always 
the methods of the natives to fall back upon, but it could not be 
said that these are bn the whole calculated to inspire much con- 
fidence, and this for the pimple reason that the native collectors 
in all parts of the world never show the slightest regard lor the 
trees they are tapping. If they do not actually cut the trees down, or 
