ASSAM, JAVA, PENANG, AND RANGOON.—Assam rubber is derived 'tiniest entirely from Ficus elastica, a small portion being obtained from Urostigma laccifera.
Ficus elastica grows wild along the foot and in the low tropical valleys of the Himalayas, from the Mechi River on the Nepal boundary at 88° E. long., to the extreme eastern limit of Assam, in 79° E. long., as well as along the feet and in the valleys of the southern mountains of the Brama putra valley, viz. the Patkye, Naga, Khasi Jynteah, and Garrow Hills. lt is not abundant until east of the Bor Nuddi, where it is common in the forests at the feet of the hills in the Khaling, Buri-goma, and Kuriapara Duars, between the Bor Nuddi and Mura Dunairi Nuddi ; the rubber has been exported from these forests, which extend over about 40 sq. miles, as well as froin the low valleys of the Bhutan Hills, immediately above them, and especially from the forests in the neighbourhood of the exit of the Nunai Nuddi in the Khaling Duar and the adjoining hills, and those between the Dimjany and the Ruta Nuddis. In the Chardwar forests, between the Mura Dunsiri or Ruta Nuddi and Borali River, the plant is abundant. Between the Bilsiri and Goboru Nuddis, it is found as far as 16 miles froui the hills, but the drier climate renders the produce much less plentiful. lu the Nowdwar forests, where the climate is less moist, only the rubber obtained from trees close to the hills is good. In the Chydwar forests, the trees are found only immediately along the foot of the hills. The plant may be seen in parts of Sikkim, in the moist but rocky side-valleys of the torrents that feed the Teesta and Mahanadi rivers. It is also very abundant in the moist forest of the northern rainy zone of Burma, beyond British territory. It flourishes hest in a very moist climate and a mean temperature of 98° F. iu the shade, but will not endure stagnant water about the roots.
The collection of the rubber in Assam is conducted under rigid restrictions in the case of all trees growing in the timber reserves, but cannot he enforced in the case of scattered trees.
Immense forests of the trees existed on both banks of the Subansiri river, and on other streams, but the reckless treatment they received from native lessees of the forests caused their ruin. Iu 1876, the leasing of these forests ceased, but there is now little or no rubber left in the plains of the Lakhimpur district. It is estimated that the forest of Cachar could yield upwards of 2000 cwt. of rubber annually. One district in Assam, 30 miles by 8, is said to contain 43,000 trees, many of them being 100 ft. high. According to Murton, there is little doubt that this same plant, Ficus elastica, affords the gutta-rambong of the Malay Peninsula, produced in the interior of Perak and on the Patani side of the Peninsula.
The natives who tap the wild trees slash every part of them within reach with their daos or knives. The incisions on the lower part of the stem, and on the roots which run some 30-40 ft. on the ground, are 6-18 in. long, and are made diagonally through the bark and into the wood, in an elliptical form, measuring about 3 iu. across the centre. The exudation from these wounds is received in holes dug in the earth, or in leaves folded conically ; that from the smaller cuts ou the upper branches is allowed to concrete on the spot. Accoiding to Collins, the yield of a tree in August is about 50 oz. of milk, giving 151 oz. of rubber ; sometimes the proportion of rubber falls so low as 10 per cont. He also observes that " during the cold season, October-March, the milk is scantier, but richer than in the warm weather, March-October." Mann finds the best tapping season in Assam to be February-April. Hunter states that the trees " yield most during the rains ; " he adds that a high yield for the first tapping of a tree 18 in.-6 ft. in girth is 35-40 lb. of rubber, it is then allowed 3-4 years' rest, when a second but much smaller colltetion is tnade.