( 6 ) 
estates tHinned in this manner, and the results 
depend on the intensity and thoroughness of the 
selective thinning. It would be advisable for each 
large estate to mark its best area for seed production 
and to adopt a very strict programme of thinning 
on an area say of one hundred acres for this purpose. 
In a block of this nature the intensity of the selection 
of parent trees could be increased from without 
inwards in such a way that the middle twenty acres 
would contain only sound, well developed trees of 
pronounced yielding ability. The seed for the nur- 
series for supplying new clearings could then be 
taken from the innermost five acre block. Such 
seed, resulting from cross pollination between high 
yielding trees, can reasonably be expected to produce 
trees of better yielding capacity than the average 
progeny derived from seed which has not been 
selected in any way. 
At the same time, it must be understood that the 
progeny from seed selected in this manner is likely 
to contain a proportion of poor yielding trees because 
the constitution of the parent trees is unknown; 
but on well-managed estates this proportion would 
soon be reduced considerably by ordinary selective 
thinning operations. Thus, though plantations of 
better yielders than the average are likely to result 
from this method of seed selection, the method can 
never give rise to a uniform highly productive 
plantation, because it is based on the chance 
combinations of hereditary characters in previous 
generations of cross-fertilised trees ; it is a useful 
method, however, that can easily be put into practice. 
Pedigree seed selection is by far the best means 
of improving our plantations permanently, but can 
only be attempted by trained Botanists, preferably 
