RUBBER PLANTING 43 



keeping pace by branching with the increase in cir- 

 cumference of the stem. In Funtumia the whole of the 

 adult laticiferous system is derived in this way from 

 eight primitive cells which are already present in the 

 embryo. How such a system is renewed, after the 

 latex has been drawn off by tapping, does not appear 

 to be clearly understood. As a matter of fact some 

 months must elapse after a tree of Funtumia or Castilloa 

 has been tapped, before a full supply of latex can be 

 drawn off again, whereas in the case of Hevea and 

 Manihot tapping can be carried out daily without any 

 diminution of flow. 



Latex Vessels. 



In Hevea and Manihot, latex vessels are formed in 

 an entirely different manner by the fusion of rows of 

 cells derived from the cambium. These cells arise by 

 the division of cambium cells in precisely the same way 

 as any other cells of the inner bark. When first formed 

 they are more or less brick-shaped. They are nearly 

 square in section and their length is three or four times 

 as great as their breadth. The particular cells which 

 ultimately fuse to form the latex vessels are arranged in 

 the form of a network which is generally one cell thick. 

 The meshes of which the network is composed consist 

 of one or two rows of cells, and are elongated in the 

 direction of the length of the stem. The walls which 

 intervene between the separate cells of the same network 



