RUBBER 



RUBBER 



555 



Although latex occurs in all parliS of the tree, 

 that which is found in the upper branches and 

 twigs is weak and of no talue commercially. It is 

 therefore from the lower part of the trunk, and, in 



Fig. 791. Mevea Brasiliensis, or Paia rubber tree, thirty- 

 years old. 



Picus, from the aerial roots also, that the rubber is 

 derived. 



The value of the rubbers of different trees is by- 

 no means the same. That of the Hevea is much 

 the most valued, and consequently this tree is the 

 most extensively cultivated of the four mentioned. 

 This seems to be due to the fact that 

 this rubber contains less resin than do 

 the other rubbers. In Hevea there is 

 also a perceptible difference in the 

 quality and quantity of latex obtain- 

 able from different trees. 



Culture. 



As there are some important differ- 

 ences in the way that each kind of tree 

 requires to be treated, both in the mat- 

 ter of cultivation and preparation of 

 the rubber, it will be advisable to treat 

 of each kind separately. Because of its 

 importance, and inasmuch as some of 

 the practices employed in raising Para 

 rubber apply to all the others, or 

 will serve to illustrate the general 

 principles, this species is discussed at 

 length. 



Para rubber {Hevea Brasiliensis). Figs. 790- 

 793. 



The Para rubber is a native of the tropical 

 forests bordering the Amazon river and its tribu- 

 taries, where it grows in a damp, hot climate, with 

 a heavy rainfall, and with no distinct dry period. 

 It is therefore suited for those parts of the world 

 which lie close to the equator, and are known as 

 the tropical rain-forest region. It thrives in the 

 West Indies. The temperature at which it grows 

 shows a mean annual of 78° Pahr ; mean maximum, 

 87° Fahr ; mean minimum, 69° Pahr ; extreme maxi- 

 mum, 93° Pahr ; and extreme minimum, 62° Fahr. 



The seed. — This tree is nearly always grown from 

 seed, for, although it is possible to raise it from 

 cuttings, this is not to be recommended. The seeds 

 in adult trees are produced more or less throughout 

 the year, but the main crop is ripe in August (in 

 Trinidad always in September and October). The 

 seeds are about an inch long, oblong-rounded, with 

 one side slightly flattened, dark brown marbled 

 with silver. They vary in size, some of the finest 

 trees giving very small seeds. They are produced 

 in a large, woody, three-celled capsule, which when 

 ripe explodes violently, throwing the seeds. 



The seed should be planted as soon as possible 

 after it ripens, as its vitality is of short duration, 

 and, unless specially treated, it dies within a week. 

 Seed sent from a distance, which has been long on 

 the way, should be soaked in water for a day 

 before planting. 



Tlie nursery (Fig. 792).— Nursery-beds are made 

 in moderately moist, rich soil, carefully worked. 

 The seeds are placed in rows about six inches apart, 

 on the flat side, and pressed into the soil for about 

 half their depth. In some regions they are not 

 covered with earth. It is advisable at flrst to cover 

 them with a light shade of leaves or branches, 

 about a foot above the ground. The seed germi- 

 nates very quickly. The plant can be removed to 

 the plantation when it is aboilt a foot tall, which 

 will be six or eight months from the time of plant- 

 ing the seed. However, it may be kept in the nur- 

 sery till much later, as it is very hardy and bears 

 transplanting at almost any age. It is advisable to 



Fig. 792. 



Ifurseries of rubber plants. One year old. The seedlings are 

 potted in bamboo joints. (Hart.) 



