I02 PLANT LIFE. 



severe cutting for rubber were riddled by the burrows 

 of these beetles. This defensive use of latex has been 

 recently questioned by Mr. Parkin, but there can be no 

 doubt that it does protect the tree from beetles, though, 

 of course, it may be of use in other ways. Many in- 

 valuable products, among them Atlantic cables, bicycles, 

 golfballs, waterproofs, etc., depend on rubber or gutta- 

 percha, so that the supply of latex is of great importance. 

 The low-lying moist forests of Brazil send to Britain 

 about 200,000 cwt. per annum. The West Coast of 

 Africa, the Malay Peninsula, and British India are other 

 important sources of supply. The world's supply of 

 rubber has been valued at i^ 15,000,000 annually. 



Resins. — Resins and Turpentines are abundantly 

 formed by Pines and other Coniferous trees in northern 

 latitudes, and are exactly of the same use to these 

 plants as the latex is to the plants of the tropical 

 jungles. On examining a cross section of a Pine Stem, 

 the resin-canals in the bark are very conspicuous. 

 They are lined by small cells which secrete the resin ; 

 the canal is not a cell, but an enlarged opening between 

 the cells or an intercellular space. If the tree is 

 wounded in any way, the white resin appears and soli- 

 difies on the surface. It follows that the grub of the 

 Giant-sawfly, of the Carpenter-bee, or Goat-moth, is not 

 likely to succeed in an attack upon trees which are full 

 of this substance. Resin is a complex body which yields 

 on distillation tar, turpentine, and other substances. 

 From the tar, pitch and essence of turpentine are formed. 

 The resin industry is a very important one. Some 

 three million acres are covered by resin forests in the 

 one district of Velsk in Russia. The resin trees are 

 allowed to grow for from 60 to 80 years, and are then 

 stripped regularly of bark for five years, when they are 



