Plants 1, 2, 3, and 9 yrs. old were separated into parts to show distribution between bark and wood, roots and stems, and among the variously aged segments of stems. As normally harvested, 2/3-3/4 of the rubber is in the above-ground branch system. Both rubber and resins are more concentrated in the bark than in the wood. For the plant as a whole, the bark has about 3 times the rubber conc. of the wood, and carries 3/4-4/5 of the total rubber. Although rubber conc. in the entire plant or in a segment of the plant axis increases as it becomes older, variously aged stem segments on the same plant tend to have rather similar rubber conc. This is in part due to the fact that the proportion of rubber-rich bark increases progressively from the oldest stem segments to the youngest. Much of the rubber in dead stems changes to acetone soluble substances within a few months of field exposure. The increase in rubber conc. as a stem becomes older seems to be partly due to continued rubber accumulation in the older cells over a period of several years. The inner annual rings in an old stem show a much higher rubber conc. than do the outer ones.