Alba, 
-Castilloa elastiea alba produces a thick creamy milk. It 
is the hardiest of all Castilloa trees, and suffers very little from the 
tapping operaiion. ft also yields the largest quantity of rubber. 
The bark of this variety is white, # with a distinct yellowish or 
pinkish cast. 
Negra. — Castilloa elastiea negra is characterised by a very rough 
dark bark. It yields very readily a thin milk producing a good 
| rubber, but the tree in tapping easily bleeds to death. 
Rubra. — Castilloa elastiea rubra has a reddish bark which is 
very smooth, thin, and brittle ; nor does it show the longitudinal 
furrows which are noticeable in the two first-named trees. This 
variety yields a very small quantity of milk, but the rubber.obtained, 
from it is good. The tree is very common all over Central America, 
and I am afraid that in a number of instances it was this tree which 
was planted instead of the white Castilloa. Indeed, Koschny is 
inclined to think that it is this variety with which the experiments 
in the Botanical Gardens in Ceylon and Java were made which gave 
such discouraging results. 
Shade or Open. — The question whether Castilloa should be 
planted in the shade, or in open land has been answered both ways. 
It is possible that the climatic conditions of the district in which 
the plantation is situated may have some influence upon this point. 
However, all the reliable evidence seems to show that the trees 
grow badly in dense forests, and produce a poor yield of rubber 
when grown on open ground. They appear to prosper best when 
growing up together with other trees, so that the trunk is always 
shaded, whilst the top of the tree at least, for a certain time during 
the day, receives the direct rays of the sun, from what I have 
seen at Las Cascadas 1 entertain no doubt whatever, the last 
named condition is the most favourable for the growth of the trees. 
CLEARING. libs being admitted, it is obvious that in planting 
Castilloa in open land it is necessary to plant at the same time trees 
to protect and partly shade it. As this adds very greatly to the 
cost of planting, it stands to reason that in selecting land for the 
cultivation of Castilloa, preference should be given to forest land 
T he larger trees are cut out-there are generally plenty of uses for 
them on the plantation— only the smaller trees "being left standing 
between which the rubber trees are planted. 
Scml.— A s regards the configuration of the land, and the best 
quality or the soil, some little discrimination is also required 
Regarding the sod, it may be said that Castilloa is very modest 
indeed, but, of course, this does not mean that just anv soil is good 
enough. The best results are undoubtedly obtained on a deep 
loamy, only moderately sandy soil. Whether Castilloa should be 
planted on level or on hanging ground is a rather more important 
question In Mexico, I believe, rather large level tracts have been 
planted, but then the rainfall in Mexico is considerably less than 
* V 5 ,n Colombia. It is quite certain that the trees require 
for ^ and ^ Wlth a rainfal! of T 3° inches, the figure 
ie s mus, means hanging land. 1 here are immense traces 
