IN CEYLON. 
25 
length of the members of the vessels from 030 to 0*54 mm. 
This constancy in size throughout the genus in Ceylon is one 
of the main characters of the timbers. When one considers 
the climatic differences between Mannar and Adam’s Peak 
Wilderness, one is led to expect that there will be great 
differences in the size of the water storing and conducting 
tissues in the species growing at these places, but such 
differences are by no means pronounced. 
There is very little variation in the form of the members 
of vessels. In the heartwood the small-lumined vessels are, 
when isolated, approximately spherical or crudely hexagonal 
in transverse outline, but as one passes to the sapwood the 
increase in dimensions is more in the radial than the tangen¬ 
tial direction, and as, a consequence a radially elongated 
element presents itself. When the members are grouped, 
however, the spherical or elongated outline is rarely met 
with, one or more sides become straight, and the tangential 
diameter of each member is usually considerably more than 
the radial. 
The sides of each member are characterized by a straight 
vertical course, and the original transverse partitions are 
only slightly inclined to the horizontal. 
The walls of the vessels vary in thickness from 0*002 to 
0*0035 mm. They are usually very well pitted. They are 
composed mainly of lignin, which continues to respond to 
the safranin and fuchsin tests even when considerably dis¬ 
coloured, and the lumina partially filled with coloured 
materials. 
The function is probably that of storing or even conduct¬ 
ing water, but when once the lumina are filled with gum and 
resin this function must be taken up by the younger 
tracheal elements. The vessels do not undergo depletion of 
coloured contents, the infiltrating materials increasing from 
time to time until the vessels are completely blocked. 
Tracheids .—There is not very much to be said about these 
elements. They are only very sparsely distributed, and in 
8(1)4 ' (4) 
