42 RUBBER AND 



for the descent of sap, these additions include in certain 

 cases new vessels for the storage of latex. We shall see, 

 however, that in the majority of latex-producing plants, 

 the growth of the laticiferous system is independent of 

 the cambium. 



The laticiferous system. 



The channels, which contain the latex, occur in leaves, 

 stem and roots. They are already present in the young 

 seedling, and they may also occur in the fruits and 

 seeds. In the stem and roots these passages are usually 

 confined to the bark. The laticiferous channels may 

 arise in the bark in one or other of two distinct ways, 

 characteristic of different groups of plants, and the 

 resulting passages are distinguished as latex tubes and 

 latex vessels respectively. 



Latex Tubes. 



The type of channel which is characteristic of the 

 majority of latex-producing plants, although not of the 

 most important species from the point of view of 

 rubber-production, is known as a latex tube. So far 

 as is known latex tubes are never renewed from the 

 cambium. The tubes arise in the seedling in the form 

 of a small number of closed cells, which appear to be 

 capable of almost unlimited growth and extension. As 

 the seedling grows, these tubes also grow and insinuate 

 themselves between the growing cells of the cortex, 



