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for one complaint, which for another, and so on. Only by such 
involuntary study could the extensive knowledge which exists 
among the natives of tropical countries as to the uses of the 
local flora have been acquired. In every country the people 
know in detail what plants are useful, what harmful. The next 
stage above this may be seen in thinly peopled districts in 
many tropical countries, when the elements of cultivation come 
in. The people fell and burn the forest, cultivate a crop or 
two on the land thus cleared, and then abandon it, when it 
grows up in scrubby jungle, and may be again cleared after 
the lapse of ten to fifty years. There is no tillage worth men- 
tion, but definite crops, whose value was learnt in the earlier 
stages of agriculture, are sown or planted for the sake of 
a return. Such a system is known as “ladang” in Malaya, 
“chena” in Ceylon, “jhuming” in India, and is still very widely 
spread. In ladang-cultivation the best of the useful plants that 
were discovered in the earlier stage can be picked out, and 
thus for the first time a definite selection and improvement 
comes in. 
The next stage ae ladang is twofold. On the one side 
we have “mixed gardens”, on the other “fields” of annual crops. 
The mixed garden was perhaps the earlier of these, and may 
to this day be seen in the full vigour of its development in 
Java or Ceylon, and in fact throughout the tropics. Nearly 
every villager has such a garden around his house, of any size 
up to an acre or more. In it he grows a mixture of all kinds 
of useful trees, shrubs, and herbs. He does not arrange these 
in any definite way, but grows them anyhow, all over the 
ground, a mango next to a durian, and both to a coconut, 
while all sorts of small plants fill in the, spaces between. He 
does not cultivate the soil, but allows it to form a sod of 
_ grass between the trees and plants, and upon this grazes a 
few miserable cattle. 
__ The field of annual crops was probably derived independently 
from the “chena” , by cultivating it in a permanent manner with 
_ Small crops, while from either this field, the mixed garden, or 
