FORMATION OF NODULES. 
277 
situated inside an area of abnormal cortex. In other cases 
the abnormal areas consist of twisted and curved cells with 
abundant tannin content ; often these cells are disposed in the 
form of a whorl, and have been derived from cortical cells by 
indefinite division, the tannin content apparently not having any 
inhibitory action on cell division. The cortical cells surrounding 
abnormal areas always have an abundant tannin content. 
A case was observed where altered latex vessels occurred 
in the inner cortex near the stem cambium ; they were sur- 
rounded by a layer of tannin cells, and cell division had just 
set in. The same section showed a developing globular shoot 
with its vascular connection almost joined to the stem wood, 
the whole being in contact with some altered latex vessels in 
the inner cortex. This appears to be a satisfactory case of the 
production of a globular shoot from an adventitious bud in tissue 
stimulated to activity by the presence of altered latex vessels. 
Sections of both nodular cortex and normal cortex 
frequently exhibit brownish -coloured streaks. These coloured 
streaks are most abundant in nodular cortex, and occasionally 
are seen in the above-mentioned areas of abnormal tissue and 
near developing nodules. This brown colouration appears 
to be confined to the walls of the latex vessels ; it gives no 
reaction with iron salts. 
The bright yellow colouration and highly refractive walls 
of altered latex vessels in nodular cortex are quite distinct 
from the brownish-coloured cell walls above described. The 
yellow walls of latex vessels in nodular cortex have no doubt 
some connection with the chrome-yellow latex sometimes 
obtained from nodular trees ; normal latex is white. It would . 
appear probable that some substance in the altered latex 
vessels of nodular cortex is of a yellow colour, and imparts 
this colour to the walls. In some cases nodular cortex yields 
a normal white latex ; here probably the alteration of the 
latex vessel content has ceased. 
Nodules to a small extent are shed with the bark scales. 
On old Hevea trees in the Royal Botanic Gardens, Peradeniya, 
the writer has found dead nodules of fair size in dead bark 
scales which were on the point of dropping to the ground. 
One such nodule was 2 inches long. Other large nodules were 
