Rubber. 39 
With regard to the correct spacing of Para uber, the consensus of opinion 
is that wide planting is to be recommended rather than close planting. Yet, 
however, apparently we have still some more experience to gain in this connec- 
tion, for we find that in the East a small area planted 10 feet by 10 feet (which 
is very close planting indeed) yielded last year at the enormous rate of 900 Ibs. 
of dry rubber to the acre ! 
Again it seems that if a tree of H. brasiliensis is left untapped until it attains 
quite a respectable age and a substantial girth, it will yield sometimes prac- 
tically little or no latex, whereas if it has been regularly tapped from the time 
when it has attained a girth of some 20 inches, a yard from the base, it will 
give remarkably good yields. The value, therefore, of experiments with a 
tre> which shows such varied results under different conditions of soil and 
climate, must be very great, and as the Board of Agriculture’s experiments 
cover a wide range of soil and climatic conditions, the results obtained in the 
future should prove of exceptional value and interest. 
Tt is important and encouraging to remember that Mr. John Parkin, M.A., 
F.L.S., has expressed the opinion, on scientific grounds, that there should be no 
“marked difference in the quality of the rubber drawn from ten-year-old 
trees as compared with twenty-year-old ones as in both cases the latex is formed 
from secondary growth and is not comparable with that derived from lactiferous 
vessels of primary growth in the twigs and leaves.” In other words the “ differ- 
ence in the age of the trees, say from five to twenty years old, appeared to have 
little or no effect on the physical qualities of the vulcanized rubbers.” (Mr. H. 
P. Stevens quoted in Tropical Agriculturist.) 
One interesting question appears to be still unsettled, in connection with 
rubber, and that is the function of the latex. We know that the removal of 
latex does not seem to damage the tree in any way, and yet there has not yet 
been found quite a satisfactory answer as to its function. Whether it is for 
nutrition, or as a water supply, or for protective purposes, are all theories that 
have been advanced from time to time. 
The various methods of tapping Hevea trees are now well-known, possibly the 
most popular method employed is that known as the “ half-herring bone sys- 
tem,” but it has been more or less definitely settled that it is not profitable to 
tap higher than six feet from the base of the tree. It is now also generally 
recognized that too much care cannot be given to tapping operations. It is not 
unusual to find that the space between the oblique cuts, which consists of twelve 
inches of bark, can be made to last considerably over two hundred successive 
tappings—the removal of the thinnest shavings of bark possible, is the objective 
aimed at. It need hardly be emphasised that the wound or incision must not 
destroy the cambium layer ; so as to prevent this, as far as practicable, special 
knives have been invented, which are admirably suited for the purpose in view. 
I have used the No. 1 safety knife and the farrier knife with success. So as to 
save the area of bark, resource was had to pricking with a tool specially made for 
this purpose, but, of late, this practice does not seem to have found favour with 
the authorities on this subject. As might have been expected various exper!- 
ments have been carried out by scientific and practical men in connection with 
