CAOUTCHOUC AND GUTTA-PERCHA. 31 



Islands, the juice of which, as a sweet milk, or evaporated to a jelly, is taken as a 

 great delicacy, and the Banyan tree (Ficus reUgiosa Fig. 75). Many of these juices 

 also contain medicinal properties of great value. 



Secondly In the production of caoutchouc, or India-rubber. This invaluable sub- 

 stance is found in all plants, but more particularly in the Fig, Euphorbia, and Cactus 

 trees of the East Indies, South America, and Africa within the torrid zone. Of all 

 these, the fig, known as the Ficus, or Siphonia elastica, is the most valuable ; but in the 

 countries where the manufacture of India-rubber is a daily occupation, it is not 

 exclusively selected. This increased quantity of caoutchouc in the latex of hot cli- 

 mates is believed to be due to the powerfully elaborating property of the sun's rays in 

 those climates. 



The following is the mode in which the India-rubber is prepared from the milky 

 juice : 



The natives having selected a fine specimen of the Siphonia elastica, sixty feet in 

 height, make deep incisions into its smooth, brownish-gray bark; after which the 

 white juice flaws forth in considerable abundance. Before it dries upon the trunk, or 

 in a hole at the foot of the tree, it is spread over bottles of unburnt clay, and dried 

 over a smoking fire ; care being taken to prevent the flame burning it. When it is 

 dried, another coating of the juice is placed upon it, and that again is he^d over the fire ; 

 and the process is thus repeated, until the required thickness has been attained. When 

 the process is completed the bottle of clay is broken and the pieces extracted ; after 

 which the Indian-rubber is ready for the market. It is met with in commerce of various 

 colours, terminating in a deep black ; but the juice is originally colourless, and the 

 colour is produced by the smoke in which it is immersed in the process of drying. 



This tissue is found in all parts of a plant ; but, from its ramifications amongst 

 other tissues, cannot be readily separated. It is most readily seen in the fresh stipules 

 of the Ficus elastica. 



Gutta-percha is another invaluable substance, recently obtained from the latex 

 of certain plants, and especially of the class called Sapotacea, abounding in the Indian 

 Archipelago. The trees whence it is obtained are large, but not otherwise valuable. 

 The gutta-percha is obtained by incising the bark and collecting the milky juice, which 

 speedily coagulates. Each tree yields from twenty to fifty Ibs., so that the destruction 

 of a large number of trees is required in order to meet the present enormous demand 

 for this article of commerce. It appears that the proper term is Gutta-Pulo-Percha 

 gutta signifying gum in the Malay language, and Pulo-Percha the island whence it is 

 obtained. When translated into English words, it is " gum of the ragged island." 



The Secretions of Plants. We now proceed to describe the chief secretions 

 of plants, some of which are of the utmost value to man. They are Starch, Eaphidcs, 

 Silica, Oils, and Fats, and the colouring principles of plants. 



Starch. This alimentary substance was, until recently, believed to be peculiar to 

 vegetables ; and, although it is not strictly, it is almost exclusively confined to them. 

 It is, moreover, the chief element in vegetables, which renders them fit to be the food of 

 animals, and enjoys, therefore, a position of the utmost importance. Starch is not to 

 be understood as directly represented by the article of commerce which bears its name ; 

 for, although that is starch, it has been so prepared as to lose the anatomical charac- 

 teristics which starch in its'natural state possesses. All plants, probably, possess this 

 substance, but in very unequal degrees ; and it is only when it" exists in quantities 

 much greater than the plant requires for its own purposes that it is sought after by 



