76 
Notes. 
In two other cases medullary tubes seemed to come directly from the 
vascular ring, but they had been cut across and could not be traced 
between its elements. 
Connections between the medullary and cortical laticiferous tubes 
may occur in young internodes, and may be obliterated as secondary 
thickening proceeds. Older seedlings would be required to determine 
this. 
In the hypoderm or outer cortex of the upper part of the stems of 
the older seedlings laticiferous tubes also occur 1 . They seem to arise 
as branches from the main system of tubes in the inner cortex. 
Branches from these tubes are frequently found running obliquely 
upwards through the cortex, passing between the elements of the 
sclerenchymatous sheath, and continuing their course in the hypo- 
dermal tissue. 
In Manihot Glaziovii no connections between the hypodermal and 
cortical systems were observed except at the nodes, but seedling plants 
were not examined. Probably the two systems may be quite as dis- 
tinct in the internodes of mature plants of Hevea brasiliensis. The 
condition of the laticiferous tissue at the nodes closely resembles that 
in Manihot , the sclerenchymatous sheath being interrupted, and the 
abundant and irregular branching making it difficult to distinguish 
between the two systems. Hypodermal laticiferous tubes were only 
found in the upper half-inch of the first internode of the epicotyl and 
in the succeeding short internodes. 
Blind endings. The ultimate ramifications of the laticiferous tubes 
of the hypodermal and medullary systems frequently become very 
narrow and appear to terminate blindly. Similar endings are found 
among the tubes of the inner cortex. They are, however, of rare 
occurrence except in the neighbourhood of a node. 
It appears, therefore, that though the laticiferous tubes in this plant 
consist mainly of vessels formed by the fusion of rows of cells 2 , yet 
these vessels, like the laticiferous cells of other euphorbiaceous plants, 
retain the power of independent growth, and may put out branches 
which grow by their apices. 
Reticulate anastomoses occur both in the hypodermal 3 and medul- 
lary systems, but are of much less frequent occurrence than in the 
tubes of the inner cortex. 
Cf. Scott, loc. cit. 
2 Scott, loc. ck. 
5 Scott, loc. cit. 
