OF PLANTS. 317 



and some of them are highly interesting. The 

 bread-fruit of- the South Sea islands (Artocarpus 

 incisv) is well known from the descriptions of the 

 voyagers ; and though its qualities have been extolled 

 far beyond what they really deserve, it is a very 

 interesting and, in those countries, a very useful 

 tree. But as that tree furnishes bread in one part 

 of the world, trees of the same family yield milk 

 in others. There is a sort of animal principle, not 

 a principle of animal life, but an affinity to animal 

 matter, in most of the family. That is contained in 

 the substance called caoutchouc; familiar to most 

 people as " Indian rubber," remarkable alike for its 

 elasticity, its insolubility in water, and the difficulty 

 with which it can be cut. On these accounts it is 

 now extensively used in the arts, not only for its 

 original purpose of effacing black lead from paper, 

 but as an ingredient in varnishing, in making water- 

 proof cloth, shoes, and numerous other articles. 

 Though the whole family contain more or less of 

 that substance, there are many of them, such as the 

 mulberry and the common fig, in which the quantity 

 is so small that it is not worth extracting. But 

 although the substance is procured in great quanti- 

 ties, the plants which yield the greatest abundance 

 are not very clearly determined. Indeed, it should 

 seem that the plants which produce the greater part 

 of the caoutchouc of commerce belong to other 

 families. That of Sumatra, and the other islands 

 on the south-east of Asia, is obtained from some 

 species of Urceola. One of them, the elastic, is very 

 plentiful in Palo Penang, or Prince of Wales' Island. 

 It grows to about the thickness of a man's arm, and 

 is cylindrical, with pale bark, very much cracked. 

 It runs along the ground, striking roots, but very 

 seldom putting out branches ; and it will run in that 

 way to the distance of five hundred feet ; but when 

 it encounters trees, it climbs up the stems and 

 spreads among the branches. The quantity of juice 



Dda 



