288 
BRYCE : 
Thus, in the absence of altered latex vessels in the core, these 
are not typical nodules, nor are they to be classed with nodules. 
In two trees structures were obtained which showed the 
central core to be composed of portions of cortical tissue 
without latex vessels, and thus these differ still more 
widely from typical nodules. These latter were obtained 
from the cortex where the bark had no special markings 
externally. 
It would appear therefore that Hevea cortex is capable of 
developing woody bodies as the result of various disturbances 
in the cortex. 
In the production of vascular connections with the 
stem nodules may exhibit a sort of polarity, as in the 
production of vascular connections by globular shoots on their 
inner surface. Some of the vascular connections of nodules 
may be derived from latent buds or globular shoots which 
have been caught up and absorbed by the nodule in its 
development. 
There still remains to be determined the nature and cause 
of the alteration in the latex vessel content, and any advance 
in this direction will depend on advance in our knowledge of 
the constitution of latex and its function in the internal 
economy of Hevea bmsiliensis. 
4» Summary. 
1 . Nodules are produced in the cortex of Hevea hrasiliensis 
as the result of an alteration in the latex vessel content. 
2. This alteration has not been connected with the attack 
of any parasitic organism, but appears rather to be due to 
physiological changes in the latex. 
3. The tendency to suffer alteration in the latex vessel 
content appears to be confined to certain individual trees 
which have a predisposition to develop this condition. 
4. Four types of nodule have been distinguished : — 
(а) Nodules formed round altered latex vessels. 
(б) Nodules formed round lesions in the cortex into which 
latex has oozed and coagulated. May occur in 
any Hevea tree. 
