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, keeping pace by branching with the increase in circumference 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.