the roots, and not as a regular storehouse of nutriment from which 
the plant can at once take up the full of its requirements. I well 
remember an eminent Chemist remarking to me on the excessively 
barren character of the soils of the interior in certain parts of the 
mainland, as shown by analysis, and yet these same lands had 
grown large tracts of forest and the trees were giants. There can 
be no doubt whatever that such growth is due, not to the natural 
or contained fertility of the soil, but to the incidental increment 
which is continuously being added in the course of seasons by 
natural accumulations. That leaves and flowers have long been 
known as fertilizers of no mean kind by practical men goes with- 
out saying, but the exact manner in which nutriment is taken up 
and the exact quantity of plant food which is annually derived 
from this source is yet to be fully determined. In a recent paper 
on the flowers of the “ Bois Immortel ” or Erythrina sp. (reprinted 
in this Number) the large proportion of nitrogen which they con- 
tain was pointed out and an argument was based upon it for the 
continued use of this tree for shading cacao plantation. It has 
been known, however, that the flowers of all kinds of trees contain 
large amounts of nitrogen, and that it is quite as probable that 
the flowers of any trees that might be substituted as shade for 
cacao would contain as much nitrogen as the “ Immortel 
There can be no doubt whatever that this incidental increment 
is valuable, as are many others as yet undiscovered or unrecognis- 
ed, especially so the amounts of nitrogen distributed by the crops 
of seed from leguminous trees, which fall and rot, for the most 
part upon the ground. The incidental increment deposited in the 
form of the excreta of birds, reptiles and insects, and by the death 
and decay of their bodies is as yet an uncalculated item, and yet it 
will be found on -examination that it is sufficient to account for the 
supply of certain plant food which would be otherwise absent. 
The lime and phosphate in the bones of an animal or reptile is 
comparatively small, but still their bodies give to the soil consti- 
tuents, which it requires for nourishing certain kinds of plants. It 
is often argued that as so many thousand bushels or bags of cacao 
are sent out of Trinidad that the soil must in time become ex- 
hausted, and the argument follows this line when a supply of 
nitrogen from the flowers of the “Immortel” is spoken of. We 
find, however, cacao plantations in full bearing which have been 
under cultivation 50 or 60 years and producing to-day as much as 
in the first instance, and without artificial manure. We might be 
told that the supply of plant food naturally existed in the ground 
and was made available as required. If we accept this, then it is 
clear we ought to be able to ascertain exactly by analysis how 
much food the soil contains and how long the supply will last. 
But this has as yet never been done, for there has always been the 
“ incidental increment ” which daily and hourly accumulates to 
upset this addition and subtraction theory, which is so neatly pro- 
pounded in many cases in the teaching of non-practical men. We 
are told that so many tons of plant food is removed, but we seldom 
get the amount per tree, as the amount would appear too insign i- 
