Naturalisation in Extra-Tropical Countries. 227 



3,500,000 [J. G-. Baker]. Markham and Collins pronounce the 

 caoutchouc of F. elastica not quite so valuable as that of the 

 Heveas and Castilloas of South- America. Heat and atmospheric 

 moisture greatly promote the growth of F. elastica. Like most other 

 Fig-trees, it is easily raised from seed. A tree of F. elastica is 

 tapped in Assam when twenty-five years old. After fifty years the 

 yield is about 40 Ibs. of caoutchouc every third year, and lasts till 

 the tree is over 100 years old. The milky sap, flowing from cuts in 

 the stem, is poured into boiling water and stirred till it gets firm ; or 

 the sap is poured into large bins partly filled with water ; the fluid 

 caoutchouc-mass after a while floats on the surface, when it is taken 

 out and boiled in iron-pans, after the addition of two parts of water, 

 the whole being stirred continuously ; after coagulation the caout- 

 chouc is taken out and pressed, and if necessary boiled again, then 

 dried, and finally washed with lime-water. The sap from cuts into the 

 branches is allowed to dry on the trees [J. Collins]. Dr. S. Kurz 

 states, that F. laccifera (Roxburgh) from Silhet is also a caoutchouc- 

 tree, and that both this and F. elastica yield most in a ferruginous 

 clay- soil on a rocky substratum ; further, that both can bear dryness, 

 but like shade in youth. Several other species of tropical figs, 

 American as well as Asiatic, are known to produce fair caoutchouc, 

 but it is questionable, whether any of them would prosper in extra- 

 tropical latitudes ; nevertheless for the conservatories of botanic 

 gardens all such plants should be secured with a view of promoting 

 public instruction. To give some idea of the vastly increasing 

 extent, to which "Rubber" is now required, it may be stated, that 

 at Wetzell's factories in Miinden and Hildesheim alone during 1884 

 were produced 100,000 Ibs. of surgical articles; 100,000 Ibs. valves, 

 buffers and washers; 150,000 Ibs. hose and belting; 200,000 Ibs. 

 insertion-sheets and tucks-packings; 250,000 dozens of fancy-coloured 

 balls, irrespective of other rubber-articles ; this factory which exists 

 since 1868, is employing 600 workmen and operating with machinery 

 equal to 300 horse-power. Caoutchouc has been recommended also 

 for inner-lining of war-ships [G-. A. F. Wilson]. Ficus Vogelii 

 (Miquel) yields in Liberia and Lagos a kind of rubber, lauded by 

 Messrs. Warne and Christy. The Columbian Rubber-tree is Sapium 

 biglandulosum (J. Mueller). 



Ficus infectoria, Roxburgh. 



India, ascending to 5,000 feet. Probably hardy where frosts are 

 only slight, and then adapted for street-planting. Brandis and 

 Stewart found its growth quicker than that of Siris or Albizzia 

 procera. F. religiosa (Linne) ascends to the same height, and is 

 of quick growth in moist climates. It bears well the clime of 

 Beloochistan. It is one of the trees on which the lac-insect exists. 

 The fruits of some huge Himalayan species for instance, H. virgata, 

 F. glomerata (Roxburgh) and F. Roxburghii (Wallich) are edible. 

 The curious Tikoua from Yun-Nan, introduced into France by the 



