334 
Of the unidentified species two give respectively a red and white 
rubber apparently valuable, the remainder an inferior or practically 
valueless sticky rubber. These jungle rubbers are it seems very 
abundant in many parts of the region .and the rubber is collected 
by the natives. It is not collected as a rule in the wet season. The 
amount obtained in a single day by a man is estimated by two ob- 
servers as one kilogramme (2 lbs. 3 ozs.) and by others very much 
less from 90 to 100 grammes (1,500 grains). A vine about .10 metre 
(3I inches) in diameter at the base gives 200 grammes a year. As 
is done in the Malay Peninsula, the natives where they find a variety 
of rubber vines, mix the rubber obtained. 
The seeds of Ecdysanthera , and one of the unidentified species 
collected at the end of the dry season too x about 2 months to ger- 
minate. The seeds should not be covered with soil more than just 
enough to prevent their being washed away by watering or heavy 
rain. They require a fair amount of shade, plants unsufficiently 
protected from the sun being killed. M. Achard however prefers 
propagating these rubber vines by cuttings, and states that the best 
results were obtained with stems a little thicker than a pencil. 
Marcottage gave good results but was too troublesome. The 
growth is said to be rapid and they attain their full growth in six 
or seven years. 
The discovery of any additional rubber producing plants in any 
part of the world is always interesting, even although their value 
may not be very great. It is noticeable that none of these new 
rubber vines as far as identified belong to the genera Willughbeia 
or Urceola , which have supplied the best rubbers of the Asiatic 
forests, but to genera which as rubber producers ( Paramsria ex- 
cepted) have been quite neglected. The cultivation of rubber vines 
on a large and profitable scale still offers many difficulties. Many 
though attaining a large size in the forests, seem to grow slowly 
and make stems so slender that it is very difficult to see how to 
extract the rubber except at a prohibitive cost. The methods of 
extraction from the dry bark may eventually help to solve the diffi- 
culty, but the main crux at present is to get the plants to produce 
large enough stems to be worth the expense of barking. At pre- 
sent the rubber-vines which seem under open cultivation to produce 
the largest stems are the Landolphias of which several species are 
very stout and strong growers. The plan of growing these vines 
in forest more or less thinned is expensive the plants with the 
forest occupying a large area, and 4 also requiring a great deal of 
thinning and weeding work. A tree to carry the weight of a really 
large sized Willughbeia must be of large size and is very liable 
when the vine has attained full size or is approaching it to be 
strangled, or smothered by the vine itself. The rapidity of growth 
of a rubber vine under these conditions is not yet determined, and 
it appears that in many cases where it has been approximately de- 
termined it has been very much over rated. Much depends on the 
amount of light in the forest, and the absence of under growth 
which would crowd out the young vines, and this in most tropical 
forests would entail a considerable amount of constant labour. 
