*7 
a foothold and as it is of very rapid growth, it soon grows into a 
small tree. I have noticed on some plantations that the managers 
studiously avoid cutting down the Guarumbo trees wherever they 
grow among the rubber, I was informed that this was done on 
purpose as the Guarumbo tree resembled the rubber tree so much 
that it helped to carry out the .impression of an even and good 
stand of rubber trees. Inspecting shareholders did not notice the 
difference. I am ready to believe this, as there appears no other 
reason why the Guarumbo tree should be left standing. It is not 
good as a shade tree and as it consumes a great amount of water 
aud plant food, it is decidedly detrimental in a rubber stand. 
In the natural succession of the forest trees both Cecropia and 
Castilla are secondary elements. - The seed of Castilla is so thin 
shelled and perishable that it needs a moist place in which to 
germinate as it would otherwise be destroyed by the heat of the surf. 
We therefore always find the young seedlings growing close to 
other trees which give them sufficient protection. 
Castilla depends in many other respects upon its neighbours 
for safety. It is a very brittle tree, easily broken by the wind 
and therefore needs a wind-break. ,We always find Castillas in the 
pole stage standing close to other trees, which indicates that they 
have been able to survive only by reason of the protection afforded 
by the other trees. It may be inferred that if this is true we would 
never find a Castilla standing separated from any neighbours. I 
think that in every case where an old Castilla tree is found single 
it has either been planted by man and protected, or, if a wild tree' * 
the surrounding trees have been destroyed in some way or another. 
It is at least on very rare occasions thaf> Castilla is able to live 
through the sapling and pole stages without protection against wind. 
Another way in which Castilla gets protection from neighbour- 
ing trees is that these give shelter td the ground, retain moisture, 
and prevent the soil from cracking. Castilla is very sensitive to 
these influences, as its roots do not develop properly in hard -baked 
ground. ’ 1 ’ 
Castilla does not, on the other hand, develop well in shade. 
It grows very slender, with a weak trunk and an undeveloped 
crown. The tree needs plenty of light for its foliage and it is only 
where the Castilla tree has room enough to spread its branches 
and expose its foliage to the rays of -the sun that it can successfully 
maintain its position'in the struggle for space and light. 
In districts were a distinct dry season prevails, Castilla is 
pronouncedly deciduous and drops its leaves at thatperiod of theyear, 
while in a humid region the shedding of leaves goes on all the 
year round. On the Pacific side of Sierra Maclre in Mexico, the 
dry season lasts from January to May, and the rubber tree begins 
to shed its leaves with the advent of this season, and towards its 
close the trees are almost destitute of foliage. 
It is generally stated that Castilla does not flower and set 
fruit before it has reached an age of about five years. Another 
statement is that flowering commences when the tree begins to 
develop permanent branches. My observations show that if 
Castilla is grown on good soil in a suitable climate, and if the 
